diff --git a/.run/hello world.run.xml b/.run/hello world.run.xml
index c6a40a78..85774f68 100644
--- a/.run/hello world.run.xml	
+++ b/.run/hello world.run.xml	
@@ -1,6 +1,6 @@
 <component name="ProjectRunConfigurationManager">
   <configuration default="false" name="hello world" type="Application" factoryName="Application">
-    <option name="MAIN_CLASS_NAME" value="HelloWorldApp" />
+    <option name="MAIN_CLASS_NAME" value="main.HelloWorldApp" />
     <module name="replay.replay-tests.helloworld.main" />
     <option name="VM_PARAMETERS" value="-ea" />
     <option name="WORKING_DIRECTORY" value="$PROJECT_DIR$/replay-tests/helloworld" />
diff --git a/excel/src/play/modules/excel/Plugin.java b/excel/src/play/modules/excel/Plugin.java
index c9fc82ab..a0e509c3 100644
--- a/excel/src/play/modules/excel/Plugin.java
+++ b/excel/src/play/modules/excel/Plugin.java
@@ -140,7 +140,7 @@ public void compile() {
         }
 
         @Override
-        protected String internalRender(Map<String, Object> args) {
+        public String internalRender(Map<String, Object> args) {
             throw null == r_ ? new RenderExcel(file, args) : r_;
         }
     }
diff --git a/fastergt/build.gradle b/fastergt/build.gradle
index 419c7da9..b0158ba9 100644
--- a/fastergt/build.gradle
+++ b/fastergt/build.gradle
@@ -3,6 +3,8 @@ dependencies {
   implementation('org.eclipse.jdt:ecj:3.37.0')
   implementation("org.apache.commons:commons-lang3:$commonsLangVersion")
   implementation "org.apache.commons:commons-text:$commonsTextVersion"
+  api("org.codehaus.groovy:groovy:$groovyVersion")
+  api("org.codehaus.groovy:groovy-xml:$groovyVersion")
   testImplementation project(':framework').sourceSets.test.compileClasspath
   testImplementation("org.assertj:assertj-core:$assertjVersion")
 }
diff --git a/fastergt/src/play/modules/gtengineplugin/GTEnginePlugin.java b/fastergt/src/play/modules/gtengineplugin/GTEnginePlugin.java
index 57d7bf9d..3f595b08 100644
--- a/fastergt/src/play/modules/gtengineplugin/GTEnginePlugin.java
+++ b/fastergt/src/play/modules/gtengineplugin/GTEnginePlugin.java
@@ -1,7 +1,15 @@
 package play.modules.gtengineplugin;
 
+import java.lang.reflect.Field;
+import java.lang.reflect.Modifier;
+import java.util.List;
+import javax.inject.Inject;
 import play.Play;
 import play.PlayPlugin;
+import play.jobs.Job;
+import play.mvc.PlayController;
+import play.templates.FastTags;
+import play.templates.JavaExtensions;
 import play.templates.Template;
 
 import java.io.File;
@@ -44,6 +52,42 @@ public void onLoad() {
     public void onApplicationStart() {
         // need to re-init when app restarts
         init();
+        injectStaticFields();
+    }
+
+    private void injectStaticFields() {
+        injectStaticFields(Play.classes.getAssignableClasses(PlayController.class));
+        injectStaticFields(Play.classes.getAssignableClasses(Job.class));
+        injectStaticFields(Play.classes.getAssignableClasses(FastTags.class));
+        injectStaticFields(Play.classes.getAssignableClasses(JavaExtensions.class));
+    }
+
+    private <T> void injectStaticFields(List<Class<? extends T>> classes) {
+        for (Class<?> clazz : classes) {
+            injectStaticFields(clazz);
+        }
+    }
+
+    private void injectStaticFields(Class<?> clazz) {
+        for (Field field : clazz.getDeclaredFields()) {
+            if (isStaticInjectable(field)) {
+                inject(field);
+            }
+        }
+    }
+
+    private boolean isStaticInjectable(Field field) {
+        return Modifier.isStatic(field.getModifiers()) && field.isAnnotationPresent(Inject.class);
+    }
+
+    private void inject(Field field) {
+        field.setAccessible(true);
+        try {
+            field.set(null, Play.beanSource.getBeanOfType(field.getType()));
+        }
+        catch (IllegalAccessException e) {
+            throw new RuntimeException(e);
+        }
     }
 
     @Override
diff --git a/fastergt/src/play/modules/gtengineplugin/GTTemplate.java b/fastergt/src/play/modules/gtengineplugin/GTTemplate.java
index f3147c0b..8afdfbed 100644
--- a/fastergt/src/play/modules/gtengineplugin/GTTemplate.java
+++ b/fastergt/src/play/modules/gtengineplugin/GTTemplate.java
@@ -35,7 +35,7 @@ public void compile() {
     }
 
     @Override
-    protected String internalRender(Map<String, Object> args) {
+    public String internalRender(Map<String, Object> args) {
         GTRenderingResult renderingResult = internalGTRender(args);
         ByteArrayOutputStream out = new ByteArrayOutputStream();
         renderingResult.writeOutput(out, UTF_8);
diff --git a/fastergt/src/play/modules/gtengineplugin/PrecompileTemplates.java b/fastergt/src/play/modules/gtengineplugin/PrecompileTemplates.java
index a272aa8e..3ee7c415 100644
--- a/fastergt/src/play/modules/gtengineplugin/PrecompileTemplates.java
+++ b/fastergt/src/play/modules/gtengineplugin/PrecompileTemplates.java
@@ -71,7 +71,7 @@ private DummyTemplate() {
     @Override public void compile() {
     }
 
-    @Override protected String internalRender(Map<String, Object> args) {
+    @Override public String internalRender(Map<String, Object> args) {
       throw new UnsupportedOperationException();
     }
   }
diff --git a/framework/src/play/templates/ExecutableTemplate.java b/fastergt/src/play/templates/ExecutableTemplate.java
similarity index 100%
rename from framework/src/play/templates/ExecutableTemplate.java
rename to fastergt/src/play/templates/ExecutableTemplate.java
diff --git a/framework/src/play/templates/FastTags.java b/fastergt/src/play/templates/FastTags.java
similarity index 100%
rename from framework/src/play/templates/FastTags.java
rename to fastergt/src/play/templates/FastTags.java
diff --git a/framework/src/play/templates/GroovyInlineTags.java b/fastergt/src/play/templates/GroovyInlineTags.java
similarity index 100%
rename from framework/src/play/templates/GroovyInlineTags.java
rename to fastergt/src/play/templates/GroovyInlineTags.java
diff --git a/framework/src/play/templates/JavaExtensions.java b/fastergt/src/play/templates/JavaExtensions.java
similarity index 97%
rename from framework/src/play/templates/JavaExtensions.java
rename to fastergt/src/play/templates/JavaExtensions.java
index 249ab276..e3bb256e 100644
--- a/framework/src/play/templates/JavaExtensions.java
+++ b/fastergt/src/play/templates/JavaExtensions.java
@@ -33,6 +33,7 @@
 import java.util.Locale;
 import java.util.Map;
 import java.util.TimeZone;
+import play.utils.Utils;
 
 import static org.apache.commons.text.StringEscapeUtils.escapeXml11;
 
@@ -256,16 +257,7 @@ public static String urlEncode(String entity) {
     }
 
     public static String formatSize(Long bytes) {
-        if (bytes < 1024L) {
-            return bytes + " B";
-        }
-        if (bytes < 1048576L) {
-            return bytes / 1024L + "KB";
-        }
-        if (bytes < 1073741824L) {
-            return bytes / 1048576L + "MB";
-        }
-        return bytes / 1073741824L + "GB";
+        return Utils.formatSize(bytes);
     }
 
     public static String formatCurrency(Number number, String currencyCode) {
@@ -396,7 +388,7 @@ public static String camelCase(String string) {
     }
 
     public static String yesno(Object o, String[] values) {
-        boolean value = play.templates.FastTags._evaluateCondition(o);
+        boolean value = FastTags._evaluateCondition(o);
         if (value) {
             return values[0];
         }
diff --git a/framework/src/play/templates/JavaScriptEscaper.java b/fastergt/src/play/templates/JavaScriptEscaper.java
similarity index 100%
rename from framework/src/play/templates/JavaScriptEscaper.java
rename to fastergt/src/play/templates/JavaScriptEscaper.java
diff --git a/framework/src/play/templates/SafeFormatter.java b/fastergt/src/play/templates/SafeFormatter.java
similarity index 100%
rename from framework/src/play/templates/SafeFormatter.java
rename to fastergt/src/play/templates/SafeFormatter.java
diff --git a/framework/src/play/templates/SafeFormatters.java b/fastergt/src/play/templates/SafeFormatters.java
similarity index 100%
rename from framework/src/play/templates/SafeFormatters.java
rename to fastergt/src/play/templates/SafeFormatters.java
diff --git a/framework/src/play/templates/TagContext.java b/fastergt/src/play/templates/TagContext.java
similarity index 100%
rename from framework/src/play/templates/TagContext.java
rename to fastergt/src/play/templates/TagContext.java
diff --git a/framework/src/play/templates/types/SafeCSVFormatter.java b/fastergt/src/play/templates/types/SafeCSVFormatter.java
similarity index 100%
rename from framework/src/play/templates/types/SafeCSVFormatter.java
rename to fastergt/src/play/templates/types/SafeCSVFormatter.java
diff --git a/framework/src/play/templates/types/SafeHTMLFormatter.java b/fastergt/src/play/templates/types/SafeHTMLFormatter.java
similarity index 100%
rename from framework/src/play/templates/types/SafeHTMLFormatter.java
rename to fastergt/src/play/templates/types/SafeHTMLFormatter.java
diff --git a/framework/src/play/templates/types/SafeXMLFormatter.java b/fastergt/src/play/templates/types/SafeXMLFormatter.java
similarity index 100%
rename from framework/src/play/templates/types/SafeXMLFormatter.java
rename to fastergt/src/play/templates/types/SafeXMLFormatter.java
diff --git a/framework/test/play/templates/FastTagsTest.java b/fastergt/test/play/templates/FastTagsTest.java
similarity index 99%
rename from framework/test/play/templates/FastTagsTest.java
rename to fastergt/test/play/templates/FastTagsTest.java
index a58e2480..68febfce 100644
--- a/framework/test/play/templates/FastTagsTest.java
+++ b/fastergt/test/play/templates/FastTagsTest.java
@@ -7,6 +7,8 @@
 import play.mvc.Http;
 import play.mvc.Router;
 import play.mvc.Scope.Session;
+import play.templates.ExecutableTemplate;
+import play.templates.FastTags;
 import play.utils.DummyUuidGenerator;
 
 import java.io.PrintWriter;
diff --git a/fastergt/test/play/template2/JavaExtensionTest.java b/fastergt/test/play/templates/JavaExtensionTest.java
similarity index 97%
rename from fastergt/test/play/template2/JavaExtensionTest.java
rename to fastergt/test/play/templates/JavaExtensionTest.java
index 22b928d8..0427c0be 100644
--- a/fastergt/test/play/template2/JavaExtensionTest.java
+++ b/fastergt/test/play/templates/JavaExtensionTest.java
@@ -1,7 +1,10 @@
-package play.template2;
+package play.templates;
 
 import groovy.lang.GroovyObjectSupport;
 import org.junit.jupiter.api.Test;
+import play.template2.GTTemplateRepoBuilder;
+import play.template2.TemplateRootFolder;
+import play.template2.TemplateSourceRenderer;
 
 import java.lang.reflect.Method;
 import java.math.BigDecimal;
diff --git a/framework/test/play/templates/JavaExtensionsTest.java b/fastergt/test/play/templates/JavaExtensionsTest.java
similarity index 99%
rename from framework/test/play/templates/JavaExtensionsTest.java
rename to fastergt/test/play/templates/JavaExtensionsTest.java
index fcfe97c7..b2a4dee3 100755
--- a/framework/test/play/templates/JavaExtensionsTest.java
+++ b/fastergt/test/play/templates/JavaExtensionsTest.java
@@ -6,6 +6,7 @@
 import org.junit.jupiter.api.BeforeAll;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
+import play.templates.JavaExtensions;
 
 import java.util.ArrayList;
 import java.util.List;
diff --git a/framework/build.gradle b/framework/build.gradle
index a892824d..b178c866 100644
--- a/framework/build.gradle
+++ b/framework/build.gradle
@@ -23,9 +23,6 @@ dependencies {
   implementation('ch.qos.reload4j:reload4j:1.2.25')
   implementation('org.ehcache:ehcache:3.10.8')
   api('net.sf.oval:oval:3.2.1')
-  // Groovy 4 can be found in org.apache.groovy
-  api("org.codehaus.groovy:groovy:$groovyVersion")
-  api("org.codehaus.groovy:groovy-xml:$groovyVersion")
   api('org.hibernate:hibernate-core-jakarta:5.6.15.Final')
   // Hibernate 5.6 series is only compatible with persistence-api:3.0.0
   api('jakarta.persistence:jakarta.persistence-api:3.1.0')
diff --git a/framework/src/errors/404.html b/framework/src/errors/404.html
index cfb50b43..07fb1204 100644
--- a/framework/src/errors/404.html
+++ b/framework/src/errors/404.html
@@ -1,18 +1,11 @@
-<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
-<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
-    <head>
-        <title>Not found</title>
-        <meta http-equiv="Content-Type" content="text/html; charset=${_response_encoding}"/>
-    </head>
-    <body>
-    	#{if play.mode.name() == 'DEV'}
-                #{404 result /}
-    	#{/if}
-        #{else}
-            <h1>Not found</h1>
-            <p>
-                ${result.message}
-            </p>
-        #{/else}
-    </body>
+<!doctype html>
+<html lang="en">
+  <head>
+    <title>Not found</title>
+    <meta charset="${_response_encoding}"/>
+  </head>
+  <body>
+    #{if play.Play.mode.isDev()} #{404 result /}#{/if}#{else}<h1>Not found</h1>
+    <p>${result.message}</p>#{/else}
+  </body>
 </html>
diff --git a/framework/src/errors/500.html b/framework/src/errors/500.html
index 5b4a1070..07f8d874 100644
--- a/framework/src/errors/500.html
+++ b/framework/src/errors/500.html
@@ -1,16 +1,10 @@
-<!DOCTYPE html>
-
-<html>
+<!doctype html>
+<html lang="en">
     <head>
         <title>Application error</title>
         <meta http-equiv="Content-Type" content="text/html; charset=${_response_encoding}"/>
     </head>
     <body>
-        #{if play.mode.name() == 'DEV'}
-            #{500 exception /}
-        #{/if}
-        #{else}
-            <h1>Oops, an error occurred</h1>
-        #{/else}
+        #{if play.Play.mode.isDev()}#{500 exception /}#{/if}#{else}<h1>Oops, an error occurred</h1>#{/else}
     </body>
 </html>
diff --git a/framework/src/play/ErrorHandler.java b/framework/src/play/ErrorHandler.java
new file mode 100644
index 00000000..b80bb2bd
--- /dev/null
+++ b/framework/src/play/ErrorHandler.java
@@ -0,0 +1,27 @@
+package play;
+
+import java.nio.charset.Charset;
+import javax.annotation.CheckReturnValue;
+import javax.annotation.Nonnull;
+import play.mvc.Http;
+import play.mvc.Http.Request;
+import play.mvc.Http.Response;
+import play.mvc.Scope.Flash;
+import play.mvc.Scope.RenderArgs;
+import play.mvc.Scope.Session;
+
+public interface ErrorHandler {
+
+  /** Called for errors thrown/returned by the application. */
+  void applicationErrorResponse(play.mvc.results.Error error, Request request, Response response,
+      Session session, RenderArgs renderArgs, Flash flash);
+
+  /**
+   * Called when errors originate in the framework (only 404 and 500).
+   *
+   * <p>When 'e' is of type NotFound we're dealing with a 404, otherwise it's a 500.
+   */
+  @Nonnull
+  @CheckReturnValue
+  String frameworkErrorResponse(Http.Request request, String format, Exception e, Charset encoding);
+}
diff --git a/framework/src/play/Play.java b/framework/src/play/Play.java
index 3b42126e..c0079a51 100644
--- a/framework/src/play/Play.java
+++ b/framework/src/play/Play.java
@@ -1,5 +1,15 @@
 package play;
 
+import static java.nio.charset.StandardCharsets.UTF_8;
+
+import java.io.File;
+import java.lang.management.ManagementFactory;
+import java.nio.charset.Charset;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import java.util.Properties;
+import javax.annotation.Nullable;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import play.cache.Cache;
@@ -7,31 +17,13 @@
 import play.inject.BeanSource;
 import play.inject.DefaultBeanSource;
 import play.inject.Injector;
-import play.jobs.Job;
 import play.mvc.ActionInvoker;
 import play.mvc.CookieSessionStore;
-import play.mvc.PlayController;
 import play.mvc.Router;
 import play.mvc.SessionStore;
 import play.plugins.PluginCollection;
-import play.templates.FastTags;
-import play.templates.JavaExtensions;
 import play.templates.TemplateLoader;
 
-import javax.annotation.Nullable;
-import javax.inject.Inject;
-import java.io.File;
-import java.lang.management.ManagementFactory;
-import java.lang.reflect.Field;
-import java.lang.reflect.Modifier;
-import java.nio.charset.Charset;
-import java.util.ArrayList;
-import java.util.Arrays;
-import java.util.List;
-import java.util.Properties;
-
-import static java.nio.charset.StandardCharsets.UTF_8;
-
 /**
  * Main framework class
  */
@@ -114,6 +106,8 @@ public boolean isProd() {
 
   private final ActionInvoker actionInvoker;
 
+  public static ErrorHandler errorHandler;
+
   public Play() {
     this(new DefaultBeanSource());
   }
@@ -128,6 +122,13 @@ public Play(ConfLoader confLoader, BeanSource beanSource, SessionStore sessionSt
     this.actionInvoker = new ActionInvoker(sessionStore);
   }
 
+  public Play(ConfLoader confLoader, BeanSource beanSource, SessionStore sessionStore, ErrorHandler errorHandler) {
+    Play.beanSource = beanSource;
+    Play.errorHandler = errorHandler;
+    this.confLoader = confLoader;
+    this.actionInvoker = new ActionInvoker(sessionStore);
+  }
+
   /**
    * Init the framework
    *
@@ -250,7 +251,6 @@ public synchronized void start() {
       Router.detectChanges();
       Cache.init();
       pluginCollection.onApplicationStart();
-      injectStaticFields();
 
       started = true;
       startedAt = System.currentTimeMillis();
@@ -265,41 +265,6 @@ public synchronized void start() {
     }
   }
 
-  private void injectStaticFields() {
-    injectStaticFields(Play.classes.getAssignableClasses(PlayController.class));
-    injectStaticFields(Play.classes.getAssignableClasses(Job.class));
-    injectStaticFields(Play.classes.getAssignableClasses(FastTags.class));
-    injectStaticFields(Play.classes.getAssignableClasses(JavaExtensions.class));
-  }
-
-  private <T> void injectStaticFields(List<Class<? extends T>> classes) {
-    for (Class<?> clazz : classes) {
-      injectStaticFields(clazz);
-    }
-  }
-
-  private void injectStaticFields(Class<?> clazz) {
-    for (Field field : clazz.getDeclaredFields()) {
-      if (isStaticInjectable(field)) {
-        inject(field);
-      }
-    }
-  }
-
-  private boolean isStaticInjectable(Field field) {
-    return Modifier.isStatic(field.getModifiers()) && field.isAnnotationPresent(Inject.class);
-  }
-
-  private void inject(Field field) {
-    field.setAccessible(true);
-    try {
-      field.set(null, beanSource.getBeanOfType(field.getType()));
-    }
-    catch (IllegalAccessException e) {
-      throw new RuntimeException(e);
-    }
-  }
-
   /**
    * Can only register shutdown-hook if running as standalone server
    * registers shutdown hook - Now there's a good chance that we can notify
diff --git a/framework/src/play/SimpleErrorHandler.java b/framework/src/play/SimpleErrorHandler.java
new file mode 100644
index 00000000..57a85e51
--- /dev/null
+++ b/framework/src/play/SimpleErrorHandler.java
@@ -0,0 +1,112 @@
+package play;
+
+import java.nio.charset.Charset;
+import javax.annotation.CheckReturnValue;
+import javax.annotation.Nonnull;
+import play.exceptions.UnexpectedException;
+import play.libs.MimeTypes;
+import play.mvc.Http;
+import play.mvc.Http.Request;
+import play.mvc.Http.Response;
+import play.mvc.Scope.Flash;
+import play.mvc.Scope.RenderArgs;
+import play.mvc.Scope.Session;
+import play.mvc.results.BadRequest;
+import play.mvc.results.Forbidden;
+import play.mvc.results.NotFound;
+import play.mvc.results.Unauthorized;
+
+
+public class SimpleErrorHandler implements ErrorHandler {
+
+  public void applicationErrorResponse(
+      play.mvc.results.Error error,
+      Request request,
+      Response response,
+      Session session,
+      RenderArgs renderArgs,
+      Flash flash
+  ) {
+    response.status = error.getStatus();
+    String format = request.format;
+    if (request.isAjax() && "html".equals(format)) {
+      format = "txt";
+    }
+    response.contentType = MimeTypes.getContentType("xx." + format);
+    try {
+      final String title = titleFromExceptionType(error);
+      if (response.contentType.startsWith("text/html")) {
+        response.out.write(
+            simpleErrorPageHtml(title, error, response.encoding)
+                .getBytes(response.encoding));
+      } else {
+        response.out.write((title + "\n\n" + error.getMessage()).getBytes(response.encoding));
+      }
+    } catch (Exception e) {
+      throw new UnexpectedException(e);
+    }
+  }
+
+  /**
+   * Called when errors occur in the framework.
+   */
+  @Nonnull
+  @CheckReturnValue
+  public String frameworkErrorResponse(
+      Http.Request request,
+      String format,
+      Exception e,
+      Charset encoding
+  ) {
+    final String contentType = MimeTypes.getContentType("xx." + format);
+    final String title = titleFromExceptionType(e);
+    if (contentType.startsWith("text/html")) {
+      return simpleErrorPageHtml(title, e, encoding);
+    } else {
+      return title + "\n\n" + e.getMessage();
+    }
+  }
+
+  private static String titleFromExceptionType(Exception e) {
+    if (e instanceof BadRequest) {
+      return "Bad request";
+    } else if (e instanceof Unauthorized) {
+      return "Unauthorized";
+    } else if (e instanceof Forbidden) {
+      return "Forbidden";
+    } else if (e instanceof NotFound) {
+      return "Not found";
+    }
+    return "Server error";
+  }
+
+  private static boolean isServerError(Exception e) {
+    if (e instanceof BadRequest) {
+      return false;
+    } else if (e instanceof Unauthorized) {
+      return false;
+    } else if (e instanceof Forbidden) {
+      return false;
+    } else if (e instanceof NotFound) {
+      return false;
+    }
+    return true;
+  }
+
+  private String simpleErrorPageHtml(String title, Exception e, Charset encoding) {
+    String bodyHtml = (Play.mode.isDev() || !isServerError(e))
+            ? "    <h1>" + title + "</h1>\n    <p>" + e.getMessage() + "</p>\n"
+            : "    <h1>Oops, an error occurred</h1>\n";
+    return ""
+        + "<!doctype html>\n"
+        + "<html lang=\"en\">\n"
+        + "  <head>\n"
+        + "    <title>" + title + "</title>\n"
+        + "    <meta charset=\"" + encoding.name() + "\"/>\n"
+        + "  </head>\n"
+        + "  <body>\n"
+        + bodyHtml
+        + "  </body>\n"
+        + "</html>";
+  }
+}
diff --git a/framework/src/play/TemplateErrorHandler.java b/framework/src/play/TemplateErrorHandler.java
new file mode 100644
index 00000000..218193fb
--- /dev/null
+++ b/framework/src/play/TemplateErrorHandler.java
@@ -0,0 +1,91 @@
+package play;
+
+import java.nio.charset.Charset;
+import java.util.HashMap;
+import java.util.Map;
+import javax.annotation.CheckReturnValue;
+import javax.annotation.Nonnull;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import play.data.validation.Validation;
+import play.exceptions.TemplateNotFoundException;
+import play.exceptions.UnexpectedException;
+import play.libs.MimeTypes;
+import play.mvc.Http;
+import play.mvc.Http.Request;
+import play.mvc.Http.Response;
+import play.mvc.Scope.Flash;
+import play.mvc.Scope.RenderArgs;
+import play.mvc.Scope.Session;
+import play.mvc.results.NotFound;
+import play.templates.TemplateLoader;
+
+
+public class TemplateErrorHandler implements ErrorHandler {
+  private static final Logger logger = LoggerFactory.getLogger(TemplateErrorHandler.class);
+
+  public void applicationErrorResponse(play.mvc.results.Error error, Request request, Response response,
+      Session session,
+      RenderArgs renderArgs, Flash flash) {
+    response.status = error.getStatus();
+    String format = request.format;
+    if (request.isAjax() && "html".equals(format)) {
+      format = "txt";
+    }
+    response.contentType = MimeTypes.getContentType("xx." + format);
+    Map<String, Object> binding = renderArgs.data;
+    binding.put("exception", error);
+    binding.put("result", error);
+    binding.put("session", session);
+    binding.put("request", request);
+    binding.put("response", response);
+    binding.put("flash", flash);
+    binding.put("params", request.params);
+    binding.put("play", new Play());
+
+    String templatePath = "errors/" + error.getStatus() + "." + (format == null ? "html" : format);
+    String errorHtml;
+    try {
+      errorHtml = TemplateLoader.load(templatePath).render(binding);
+    } catch (TemplateNotFoundException noTemplateInDesiredFormat) {
+      errorHtml = error.getMessage();
+    } catch (Exception e) {
+      logger.error("Failed to render {}", templatePath, e);
+      errorHtml = error.getMessage();
+    }
+    try {
+      response.out.write(errorHtml.getBytes(response.encoding));
+    } catch (Exception e) {
+      throw new UnexpectedException(e);
+    }
+  }
+
+  @Nonnull
+  @CheckReturnValue
+  public String frameworkErrorResponse(Http.Request request, String format, Exception e, Charset encoding) {
+    if (e instanceof NotFound) {
+      return TemplateLoader.load("errors/404." + format).render(getBindingForErrors(request, e, false));
+    } else {
+      return TemplateLoader.load("errors/500." + format).render(getBindingForErrors(request, e, true));
+    }
+  }
+
+  @Nonnull
+  @CheckReturnValue
+  private Map<String, Object> getBindingForErrors(Http.Request request, Exception e, boolean isError) {
+    Map<String, Object> binding = new HashMap<>(4);
+    if (isError) {
+      binding.put("exception", e);
+    } else {
+      binding.put("result", e);
+    }
+    binding.put("request", request);
+    binding.put("play", new Play());
+    try {
+      binding.put("errors", Validation.errors());
+    } catch (Exception ex) {
+      logger.error("Error when getting Validation errors", ex);
+    }
+    return binding;
+  }
+}
diff --git a/framework/src/play/data/validation/ValidCheck.java b/framework/src/play/data/validation/ValidCheck.java
index 9e05b43e..5a696c1a 100644
--- a/framework/src/play/data/validation/ValidCheck.java
+++ b/framework/src/play/data/validation/ValidCheck.java
@@ -28,13 +28,11 @@ public boolean isSatisfied(Object validatedObject, Object value, OValContext con
         }
         try {
             if (context != null) {
-                if (context instanceof MethodParameterContext) {
-                    MethodParameterContext ctx = (MethodParameterContext) context;
+                if (context instanceof MethodParameterContext ctx) {
                     String[] paramNames = Java.parameterNames(ctx.getMethod());
                     key = paramNames[ctx.getParameterIndex()];
                 }
-                if (context instanceof FieldContext) {
-                    FieldContext ctx = (FieldContext) context;
+                if (context instanceof FieldContext ctx) {
                     key = ctx.getField().getName();
                 }
             }
@@ -48,8 +46,8 @@ public boolean isSatisfied(Object validatedObject, Object value, OValContext con
             Collection<Object> valueCollection = (Collection<Object>) value;
             boolean everythingIsValid = true;
             int index = 0;
-            for(Object item : valueCollection) {
-                if(!validateObject(key + "[" + (index) + "]", item)) {
+            for (Object item : valueCollection) {
+                if (!validateObject(key + "[" + (index) + "]", item)) {
                     Validation.current().errors.add(new Error(key + "[" + (index) + "]", mes, emptyList()));
                     everythingIsValid = false;
                 }
diff --git a/framework/src/play/mvc/results/Error.java b/framework/src/play/mvc/results/Error.java
index 389167d9..f1c65c44 100644
--- a/framework/src/play/mvc/results/Error.java
+++ b/framework/src/play/mvc/results/Error.java
@@ -1,28 +1,19 @@
 package play.mvc.results;
 
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
 import play.Play;
-import play.exceptions.TemplateNotFoundException;
-import play.exceptions.UnexpectedException;
-import play.libs.MimeTypes;
 import play.mvc.Http;
 import play.mvc.Http.Request;
 import play.mvc.Http.Response;
 import play.mvc.Scope.Flash;
 import play.mvc.Scope.RenderArgs;
 import play.mvc.Scope.Session;
-import play.templates.TemplateLoader;
-
-import java.util.Map;
 
 /**
  * 500 Error
  */
 public class Error extends Result {
-    private static final Logger logger = LoggerFactory.getLogger(Error.class);
 
-    private final int status;
+    protected final int status;
 
     public Error(String reason) {
         super(reason);
@@ -36,37 +27,7 @@ public Error(int status, String reason) {
 
     @Override
     public void apply(Request request, Response response, Session session, RenderArgs renderArgs, Flash flash) {
-        response.status = status;
-        String format = request.format;
-        if (request.isAjax() && "html".equals(format)) {
-            format = "txt";
-        }
-        response.contentType = MimeTypes.getContentType("xx." + format);
-        Map<String, Object> binding = renderArgs.data;
-        binding.put("exception", this);
-        binding.put("result", this);
-        binding.put("session", session);
-        binding.put("request", request);
-        binding.put("response", response);
-        binding.put("flash", flash);
-        binding.put("params", request.params);
-        binding.put("play", new Play());
-        
-        String templatePath = "errors/" + this.status + "." + (format == null ? "html" : format);
-        String errorHtml;
-        try {
-            errorHtml = TemplateLoader.load(templatePath).render(binding);
-        } catch (TemplateNotFoundException noTemplateInDesiredFormat) {
-            errorHtml = getMessage();
-        } catch (Exception e) {
-            logger.error("Failed to render {}", templatePath, e);
-            errorHtml = getMessage();
-        }
-        try {
-            response.out.write(errorHtml.getBytes(response.encoding));
-        } catch (Exception e) {
-            throw new UnexpectedException(e);
-        }
+        Play.errorHandler.applicationErrorResponse(this, request, response, session, renderArgs, flash);
     }
 
     public int getStatus() {
diff --git a/framework/src/play/mvc/results/NotFound.java b/framework/src/play/mvc/results/NotFound.java
index 4044d009..de8c4b32 100644
--- a/framework/src/play/mvc/results/NotFound.java
+++ b/framework/src/play/mvc/results/NotFound.java
@@ -17,13 +17,13 @@
 /**
  * 404 not found
  */
-public class NotFound extends Result {
+public class NotFound extends Error {
 
     /**
      * @param why a description of the problem
      */
     public NotFound(String why) {
-        super(why);
+        super(Http.StatusCode.NOT_FOUND, why);
     }
 
     /**
@@ -31,37 +31,7 @@ public NotFound(String why) {
      * @param path  routed path 
      */
     public NotFound(String method, String path) {
-        super(method + " " + path);
-    }
-
-    @Override
-    public void apply(Request request, Response response, Session session, RenderArgs renderArgs, Flash flash) {
-        response.status = Http.StatusCode.NOT_FOUND;
-        String format = request.format;
-        if(request.isAjax() && "html".equals(format)) {
-            format = "txt";
-        }
-        response.contentType = MimeTypes.getContentType("xx."+format);
-        Map<String, Object> binding = renderArgs.data;
-        binding.put("result", this);
-        binding.put("session", session);
-        binding.put("request", request);
-        binding.put("flash", flash);
-        binding.put("params", request.params);
-        binding.put("play", new Play());
-
-        String errorHtml;
-        try {
-            errorHtml = TemplateLoader.load("errors/404." + (format == null ? "html" : format)).render(binding);
-        } catch (TemplateNotFoundException e) {
-            errorHtml = "Not found";
-        }
-
-        try {
-            response.out.write(errorHtml.getBytes(response.encoding));
-        } catch (Exception e) {
-            throw new UnexpectedException(e);
-        }
+        this(method + " " + path);
     }
 
     @Override
diff --git a/framework/src/play/mvc/results/RenderHtml.java b/framework/src/play/mvc/results/RenderHtml.java
index 222c4d38..1f07c2a8 100644
--- a/framework/src/play/mvc/results/RenderHtml.java
+++ b/framework/src/play/mvc/results/RenderHtml.java
@@ -8,7 +8,7 @@
 import play.mvc.Scope.Session;
 
 /**
- * 200 OK with a text/plain
+ * 200 OK with a text/html
  */
 public class RenderHtml extends Result {
     
diff --git a/framework/src/play/mvc/results/Result.java b/framework/src/play/mvc/results/Result.java
index 1ca11cb8..e4acbd46 100644
--- a/framework/src/play/mvc/results/Result.java
+++ b/framework/src/play/mvc/results/Result.java
@@ -12,8 +12,7 @@
  */
 public abstract class Result extends FastRuntimeException {
 
-    protected Result() {
-    }
+    protected Result() {}
 
     protected Result(String description) {
         super(description);
diff --git a/framework/src/play/mvc/results/Unauthorized.java b/framework/src/play/mvc/results/Unauthorized.java
index ce560166..bae283a5 100644
--- a/framework/src/play/mvc/results/Unauthorized.java
+++ b/framework/src/play/mvc/results/Unauthorized.java
@@ -10,12 +10,12 @@
 /**
  * 401 Unauthorized
  */
-public class Unauthorized extends Result {
+public class Unauthorized extends Error {
     
     private final String realm;
     
     public Unauthorized(String realm) {
-        super(realm);
+        super(Http.StatusCode.UNAUTHORIZED, realm);
         this.realm = realm;
     }
 
diff --git a/framework/src/play/server/ServerHelper.java b/framework/src/play/server/ServerHelper.java
index 78cb5f0c..08730b92 100644
--- a/framework/src/play/server/ServerHelper.java
+++ b/framework/src/play/server/ServerHelper.java
@@ -1,12 +1,10 @@
 package play.server;
 
+import java.nio.charset.Charset;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import play.Play;
-import play.data.validation.Validation;
 import play.mvc.Http;
-import play.mvc.results.NotFound;
-import play.templates.TemplateLoader;
 import play.utils.Utils;
 
 import javax.annotation.CheckReturnValue;
@@ -16,8 +14,6 @@
 import java.io.File;
 import java.text.ParseException;
 import java.util.Date;
-import java.util.HashMap;
-import java.util.Map;
 import java.util.stream.Stream;
 
 import static com.google.common.net.HttpHeaders.KEEP_ALIVE;
@@ -70,35 +66,8 @@ public boolean isModified(String etag, long last, @Nullable String ifNoneMatch,
 
   @Nonnull
   @CheckReturnValue
-  public String generateNotFoundResponse(Http.Request request, String format, NotFound e) {
-    return TemplateLoader.load("errors/404." + format).render(getBindingForErrors(request, e, false));
-  }
-
-  @Nonnull
-  @CheckReturnValue
-  public String generateErrorResponse(Http.Request request, String format, Exception e) {
-    return TemplateLoader.load("errors/500." + format).render(getBindingForErrors(request, e, true));
-  }
-
-  @Nonnull
-  @CheckReturnValue
-  private Map<String, Object> getBindingForErrors(Http.Request request, Exception e, boolean isError) {
-    Map<String, Object> binding = new HashMap<>(4);
-    if (isError) {
-      binding.put("exception", e);
-    }
-    else {
-      binding.put("result", e);
-    }
-    binding.put("request", request);
-    binding.put("play", new Play());
-    try {
-      binding.put("errors", Validation.errors());
-    } catch (Exception ex) {
-      logger.error("Error when getting Validation errors", ex);
-    }
-
-    return binding;
+  public String generateErrorResponse(Http.Request request, String format, Exception e, Charset encoding) {
+    return Play.errorHandler.frameworkErrorResponse(request, format, e, encoding);
   }
 
   public String getContentTypeValue(Http.Response response) {
diff --git a/framework/src/play/server/Starter.java b/framework/src/play/server/Starter.java
index 8222321a..adc9e270 100644
--- a/framework/src/play/server/Starter.java
+++ b/framework/src/play/server/Starter.java
@@ -1,12 +1,24 @@
 package play.server;
 
+import play.ConfLoader;
+import play.ErrorHandler;
 import play.Play;
 import play.inject.BeanSource;
+import play.mvc.SessionStore;
 
 import java.lang.reflect.Constructor;
 import java.lang.reflect.InvocationTargetException;
 
 public class Starter {
+
+  public static int start(String playId, ConfLoader confLoader, BeanSource beanSource,
+      SessionStore sessionStore, ErrorHandler errorHandler) {
+    Play play = new Play(confLoader, beanSource, sessionStore, errorHandler);
+    play.init(playId);
+    play.start();
+    return start(play);
+  }
+
   public static int start(String playId, BeanSource beanSource) {
     Play play = new Play(beanSource);
     play.init(playId);
@@ -28,13 +40,12 @@ public static int start(Play play) {
       constructor.setAccessible(true);
       PlayServer server = (PlayServer) constructor.newInstance(play);
       return server.start();
-    }
-    catch (ClassNotFoundException | NoSuchMethodException |
-           InvocationTargetException | InstantiationException | IllegalAccessException e) {
+    } catch (ClassNotFoundException | NoSuchMethodException |
+             InvocationTargetException | InstantiationException | IllegalAccessException e) {
       throw new IllegalStateException("Failed to start server. " +
-        "Please add the dependency io.github.replay-framework:netty3, io.github.replay-framework:netty4 or "
-        + "io.github.replay-framework:javanet to your project, and make sure it precedes "
-        + "io.github.replay-framework:framework in the runtime classpath", e);
+          "Please add the dependency io.github.replay-framework:netty3, io.github.replay-framework:netty4 or "
+          + "io.github.replay-framework:javanet to your project, and make sure it precedes "
+          + "io.github.replay-framework:framework in the runtime classpath", e);
     }
   }
 }
diff --git a/framework/src/play/templates/PrecompileTemplates.java b/framework/src/play/templates/PrecompileTemplates.java
deleted file mode 100644
index 6041f0f9..00000000
--- a/framework/src/play/templates/PrecompileTemplates.java
+++ /dev/null
@@ -1,22 +0,0 @@
-package play.templates;
-
-import play.Play;
-
-public class PrecompileTemplates {
-  public static void main(String[] args) {
-    System.setProperty("precompile", "true");
-    loadPrecompiledJavaClasses();
-    precompileTemplates();
-  }
-
-  private static void loadPrecompiledJavaClasses() {
-    System.setProperty("precompiled", "true");
-    Play play = new Play();
-    play.init("prod");
-    Play.usePrecompiled = false;
-  }
-
-  private static void precompileTemplates() {
-    TemplateLoader.getAllTemplate();
-  }
-}
diff --git a/framework/src/play/templates/Template.java b/framework/src/play/templates/Template.java
index 75d17b6c..038e6e36 100644
--- a/framework/src/play/templates/Template.java
+++ b/framework/src/play/templates/Template.java
@@ -39,7 +39,7 @@ public String render(Map<String, Object> args) {
      *            List of arguments use in render
      * @return The template result as string
      */
-    protected abstract String internalRender(Map<String, Object> args);
+    public abstract String internalRender(Map<String, Object> args);
 
     public String render() {
         return internalRender(new HashMap<>());
diff --git a/framework/src/play/templates/TemplateParser.java b/framework/src/play/templates/TemplateParser.java
deleted file mode 100644
index a5d50095..00000000
--- a/framework/src/play/templates/TemplateParser.java
+++ /dev/null
@@ -1,169 +0,0 @@
-package play.templates;
-
-/**
- * Template parser
- */
-public class TemplateParser {
-
-    private final String pageSource;
-    private int nestedBracesCounter; // counts nested braces in current expression/tag
-
-    public TemplateParser(String pageSource) {
-        this.pageSource = pageSource;
-        this.len = pageSource.length();
-    }
-
-    //
-    public enum Token {
-
-        EOF, //
-        PLAIN, //
-        SCRIPT, // %{...}% or {%...%}
-        EXPR, // ${...}
-        START_TAG, // #{...}
-        END_TAG, // #{/...}
-        MESSAGE, // &{...}
-        ACTION, // @{...}
-        ABS_ACTION, // @@{...}
-        COMMENT, // *{...}*
-    }
-    private int end;
-    private int begin;
-    private int end2;
-    private int begin2;
-    private final int len;
-    private Token state = Token.PLAIN;
-
-    private Token found(Token newState, int skip) {
-        begin2 = begin;
-        end2 = --end;
-        begin = end += skip;
-        Token lastState = state;
-        state = newState;
-        return lastState;
-    }
-
-    public Integer getLine() {
-        String token = pageSource.substring(0, begin2);
-        if (!token.contains("\n")) {
-            return 1;
-        } else {
-            return token.split("\n").length;
-        }
-    }
-
-    public String getToken() {
-        return pageSource.substring(begin2, end2);
-    }
-
-    public String checkNext() {
-        if (end2 < pageSource.length()) {
-            return String.valueOf(pageSource.charAt(end2));
-        }
-        return "";
-    }
-    
-    public Token nextToken() {
-        for (;;) {
-
-            int left = len - end;
-            if (left == 0) {
-                end++;
-                return found(Token.EOF, 0);
-            }
-
-            char c = pageSource.charAt(end++);
-            char c1 = left > 1 ? pageSource.charAt(end) : 0;
-            char c2 = left > 2 ? pageSource.charAt(end + 1) : 0;
-
-            switch (state) {
-                case PLAIN:
-                    if (c == '%' && c1 == '{') {
-                        return found(Token.SCRIPT, 2);
-                    }
-                    if (c == '{' && c1 == '%') {
-                        return found(Token.SCRIPT, 2);
-                    }
-                    if (c == '$' && c1 == '{') {
-                        nestedBracesCounter = 0;
-                        return found(Token.EXPR, 2);
-                    }
-                    if (c == '#' && c1 == '{' && c2 == '/') {
-                        return found(Token.END_TAG, 3);
-                    }
-                    if (c == '#' && c1 == '{') {
-                        nestedBracesCounter = 0;
-                        return found(Token.START_TAG, 2);
-                    }
-                    if (c == '&' && c1 == '{') {
-                        return found(Token.MESSAGE, 2);
-                    }
-                    if (c == '@' && c1 == '@' && c2 == '{') {
-                        return found(Token.ABS_ACTION, 3);
-                    }
-                    if (c == '@' && c1 == '{') {
-                        return found(Token.ACTION, 2);
-                    }
-                    if (c == '*' && c1 == '{') {
-                        return found(Token.COMMENT, 2);
-                    }
-                    break;
-                case SCRIPT:
-                    if (c == '}' && c1 == '%') {
-                        return found(Token.PLAIN, 2);
-                    }
-                    if (c == '%' && c1 == '}') {
-                        return found(Token.PLAIN, 2);
-                    }
-                    break;
-                case COMMENT:
-                    if (c == '}' && c1 == '*') {
-                        return found(Token.PLAIN, 2);
-                    }
-                    break;
-                case START_TAG:
-                    if (c == '}' && nestedBracesCounter == 0) {
-                        return found(Token.PLAIN, 1);
-                    }
-                    if (c == '/' && c1 == '}') {
-                        return found(Token.END_TAG, 1);
-                    }
-                    if (c == '{') nestedBracesCounter++;
-                    if (c == '}') nestedBracesCounter--;
-                    break;
-                case END_TAG:
-                    if (c == '}') {
-                        return found(Token.PLAIN, 1);
-                    }
-                    break;
-                case EXPR:
-                    if (c == '}' && nestedBracesCounter == 0) {
-                        return found(Token.PLAIN, 1);
-                    }
-                    if (c == '{') nestedBracesCounter++;
-                    if (c == '}') nestedBracesCounter--;
-                    break;
-                case ACTION:
-                    if (c == '}') {
-                        return found(Token.PLAIN, 1);
-                    }
-                    break;
-                case ABS_ACTION:
-                    if (c == '}') {
-                        return found(Token.PLAIN, 1);
-                    }
-                    break;
-                case MESSAGE:
-                    if (c == '}') {
-                        return found(Token.PLAIN, 1);
-                    }
-                    break;
-            }
-        }
-    }
-
-    void reset() {
-        end = begin = end2 = begin2 = 0;
-        state = Token.PLAIN;
-    }
-}
\ No newline at end of file
diff --git a/framework/src/play/utils/Utils.java b/framework/src/play/utils/Utils.java
index 0617fa20..05f511ef 100644
--- a/framework/src/play/utils/Utils.java
+++ b/framework/src/play/utils/Utils.java
@@ -120,4 +120,17 @@ public static String urlDecodePath(@Nullable String enc) {
     public static String urlEncodePath(String plain) {
         return URLEncoder.encode(plain, Play.defaultWebEncoding);
     }
+
+    public static String formatSize(Long bytes) {
+        if (bytes < 1024L) {
+            return bytes + " B";
+        }
+        if (bytes < 1048576L) {
+            return bytes / 1024L + "KB";
+        }
+        if (bytes < 1073741824L) {
+            return bytes / 1048576L + "MB";
+        }
+        return bytes / 1073741824L + "GB";
+    }
 }
diff --git a/javanet/src/play/server/javanet/PlayHandler.java b/javanet/src/play/server/javanet/PlayHandler.java
index 824c83ff..d3ce6d54 100644
--- a/javanet/src/play/server/javanet/PlayHandler.java
+++ b/javanet/src/play/server/javanet/PlayHandler.java
@@ -28,7 +28,6 @@
 import play.server.IpParser;
 import play.server.ServerAddress;
 import play.server.ServerHelper;
-import play.templates.JavaExtensions;
 import play.utils.ErrorsCookieCrypter;
 import play.utils.Utils;
 
@@ -178,7 +177,7 @@ private void saveExceededSizeError(HttpExchange exchange, Http.Request request)
         error.append(":");
         String size;
         try {
-          size = JavaExtensions.formatSize(Long.parseLong(length));
+          size = Utils.formatSize(Long.parseLong(length));
         } catch (Exception e) {
           size = length + " bytes";
         }
@@ -516,13 +515,13 @@ private void serve404(NotFound e, HttpExchange exchange, Http.Request request) t
     logger.trace("serve404: begin");
     String format = defaultString(request.format, "txt");
     String contentType = MimeTypes.getContentType("404." + format, "text/plain");
-    String errorHtml = serverHelper.generateNotFoundResponse(request, format, e);
-    printResponse(exchange, NOT_FOUND, contentType, errorHtml);
+    String errorBody = serverHelper.generateErrorResponse(request, format, e, Play.defaultWebEncoding);
+    printResponse(exchange, NOT_FOUND, contentType, errorBody);
     logger.trace("serve404: end");
   }
 
-  private void printResponse(HttpExchange exchange, int httpStatus, String contentType, String errorHtml) throws IOException {
-    byte[] bytes = errorHtml.getBytes(Play.defaultWebEncoding);
+  private void printResponse(HttpExchange exchange, int httpStatus, String contentType, String errorBody) throws IOException {
+    byte[] bytes = errorBody.getBytes(Play.defaultWebEncoding);
     exchange.getResponseHeaders().set(CONTENT_TYPE, contentType);
     exchange.sendResponseHeaders(httpStatus, bytes.length);
     try (OutputStream out = exchange.getResponseBody()) {
@@ -540,7 +539,7 @@ private void serve500(Exception e, HttpExchange exchange, Http.Request request,
       String contentType = MimeTypes.getContentType("500." + format, "text/plain");
 
       try {
-        String errorHtml = serverHelper.generateErrorResponse(request, format, e);
+        String errorHtml = serverHelper.generateErrorResponse(request, format, e, Play.defaultWebEncoding);
         printResponse(exchange, INTERNAL_ERROR, contentType, errorHtml);
         logger.error("Internal Server Error (500) for {} {} ({})", request.method, request.url, e.getClass().getSimpleName(), e);
       }
diff --git a/netty3/src/play/server/netty3/PlayHandler.java b/netty3/src/play/server/netty3/PlayHandler.java
index 02a705d1..3ce80372 100644
--- a/netty3/src/play/server/netty3/PlayHandler.java
+++ b/netty3/src/play/server/netty3/PlayHandler.java
@@ -51,7 +51,6 @@
 import play.server.IpParser;
 import play.server.ServerAddress;
 import play.server.ServerHelper;
-import play.templates.JavaExtensions;
 import play.utils.ErrorsCookieCrypter;
 import play.utils.Utils;
 
@@ -310,7 +309,7 @@ private void saveExceededSizeError(HttpRequest nettyRequest, Request request) {
                 error.append(":");
                 String size;
                 try {
-                    size = JavaExtensions.formatSize(Long.parseLong(length));
+                    size = Utils.formatSize(Long.parseLong(length));
                 } catch (Exception e) {
                     size = length + " bytes";
                 }
@@ -581,13 +580,13 @@ private void serve404(NotFound e, ChannelHandlerContext ctx, Request request) {
         HttpResponse nettyResponse = createHttpResponse(HttpResponseStatus.NOT_FOUND);
         nettyResponse.headers().set(CONTENT_TYPE, contentType);
 
-        String errorHtml = serverHelper.generateNotFoundResponse(request, format, e);
-        printResponse(ctx, nettyResponse, errorHtml);
+        String errorBody = serverHelper.generateErrorResponse(request, format, e, Response.current().encoding);
+        printResponse(ctx, nettyResponse, errorBody);
         logger.trace("serve404: end");
     }
 
-    private void printResponse(ChannelHandlerContext ctx, HttpResponse nettyResponse, String errorHtml) {
-        byte[] bytes = errorHtml.getBytes(Response.current().encoding);
+    private void printResponse(ChannelHandlerContext ctx, HttpResponse nettyResponse, String errorBody) {
+        byte[] bytes = errorBody.getBytes(Response.current().encoding);
         ChannelBuffer buf = ChannelBuffers.copiedBuffer(bytes);
         setContentLength(nettyResponse, bytes.length);
         nettyResponse.setContent(buf);
@@ -606,7 +605,7 @@ private void serve500(Exception e, ChannelHandlerContext ctx, Request request, R
             String format = requireNonNullElse(request.format, "txt");
             nettyResponse.headers().set("Content-Type", MimeTypes.getContentType("500." + format, "text/plain"));
             try {
-                String errorHtml = serverHelper.generateErrorResponse(request, format, e);
+                String errorHtml = serverHelper.generateErrorResponse(request, format, e, Response.current().encoding);
 
                 byte[] bytes = errorHtml.getBytes(encoding);
                 ChannelBuffer buf = ChannelBuffers.copiedBuffer(bytes);
diff --git a/netty4/src/play/server/netty4/PlayHandler.java b/netty4/src/play/server/netty4/PlayHandler.java
index 8834dfd1..87f50b6c 100644
--- a/netty4/src/play/server/netty4/PlayHandler.java
+++ b/netty4/src/play/server/netty4/PlayHandler.java
@@ -1,5 +1,27 @@
 package play.server.netty4;
 
+import static io.netty.handler.codec.http.HttpHeaders.Names.CACHE_CONTROL;
+import static io.netty.handler.codec.http.HttpHeaders.Names.CONTENT_LENGTH;
+import static io.netty.handler.codec.http.HttpHeaders.Names.CONTENT_TYPE;
+import static io.netty.handler.codec.http.HttpHeaders.Names.COOKIE;
+import static io.netty.handler.codec.http.HttpHeaders.Names.DATE;
+import static io.netty.handler.codec.http.HttpHeaders.Names.ETAG;
+import static io.netty.handler.codec.http.HttpHeaders.Names.EXPIRES;
+import static io.netty.handler.codec.http.HttpHeaders.Names.HOST;
+import static io.netty.handler.codec.http.HttpHeaders.Names.IF_MODIFIED_SINCE;
+import static io.netty.handler.codec.http.HttpHeaders.Names.IF_NONE_MATCH;
+import static io.netty.handler.codec.http.HttpHeaders.Names.LAST_MODIFIED;
+import static io.netty.handler.codec.http.HttpHeaders.Names.SET_COOKIE;
+import static io.netty.handler.codec.http.HttpHeaders.Names.WARNING;
+import static io.netty.handler.codec.http.HttpMethod.HEAD;
+import static io.netty.handler.codec.http.HttpResponseStatus.INTERNAL_SERVER_ERROR;
+import static io.netty.handler.codec.http.HttpResponseStatus.NOT_MODIFIED;
+import static io.netty.handler.codec.http.HttpVersion.HTTP_1_1;
+import static java.nio.charset.StandardCharsets.UTF_8;
+import static java.util.Collections.unmodifiableList;
+import static java.util.Objects.requireNonNullElse;
+import static org.apache.commons.lang3.StringUtils.defaultString;
+
 import io.netty.buffer.ByteBuf;
 import io.netty.buffer.ByteBufInputStream;
 import io.netty.buffer.Unpooled;
@@ -28,6 +50,24 @@
 import io.netty.handler.stream.ChunkedInput;
 import io.netty.handler.stream.ChunkedStream;
 import io.netty.handler.stream.ChunkedWriteHandler;
+import java.io.ByteArrayOutputStream;
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.io.InputStream;
+import java.net.InetSocketAddress;
+import java.net.URI;
+import java.net.URISyntaxException;
+import java.net.URLEncoder;
+import java.nio.charset.Charset;
+import java.util.Date;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import javax.annotation.CheckReturnValue;
+import javax.annotation.Nonnull;
+import javax.annotation.ParametersAreNonnullByDefault;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import play.Invocation;
@@ -51,50 +91,8 @@
 import play.server.IpParser;
 import play.server.ServerAddress;
 import play.server.ServerHelper;
-import play.templates.JavaExtensions;
 import play.utils.Utils;
 
-import javax.annotation.CheckReturnValue;
-import javax.annotation.Nonnull;
-import javax.annotation.ParametersAreNonnullByDefault;
-import java.io.ByteArrayOutputStream;
-import java.io.File;
-import java.io.FileNotFoundException;
-import java.io.IOException;
-import java.io.InputStream;
-import java.net.InetSocketAddress;
-import java.net.URI;
-import java.net.URISyntaxException;
-import java.net.URLEncoder;
-import java.nio.charset.Charset;
-import java.util.Date;
-import java.util.HashMap;
-import java.util.List;
-import java.util.Map;
-import java.util.Set;
-
-import static io.netty.handler.codec.http.HttpHeaders.Names.CACHE_CONTROL;
-import static io.netty.handler.codec.http.HttpHeaders.Names.CONTENT_LENGTH;
-import static io.netty.handler.codec.http.HttpHeaders.Names.CONTENT_TYPE;
-import static io.netty.handler.codec.http.HttpHeaders.Names.COOKIE;
-import static io.netty.handler.codec.http.HttpHeaders.Names.DATE;
-import static io.netty.handler.codec.http.HttpHeaders.Names.ETAG;
-import static io.netty.handler.codec.http.HttpHeaders.Names.EXPIRES;
-import static io.netty.handler.codec.http.HttpHeaders.Names.HOST;
-import static io.netty.handler.codec.http.HttpHeaders.Names.IF_MODIFIED_SINCE;
-import static io.netty.handler.codec.http.HttpHeaders.Names.IF_NONE_MATCH;
-import static io.netty.handler.codec.http.HttpHeaders.Names.LAST_MODIFIED;
-import static io.netty.handler.codec.http.HttpHeaders.Names.SET_COOKIE;
-import static io.netty.handler.codec.http.HttpHeaders.Names.WARNING;
-import static io.netty.handler.codec.http.HttpMethod.HEAD;
-import static io.netty.handler.codec.http.HttpResponseStatus.INTERNAL_SERVER_ERROR;
-import static io.netty.handler.codec.http.HttpResponseStatus.NOT_MODIFIED;
-import static io.netty.handler.codec.http.HttpVersion.HTTP_1_1;
-import static java.nio.charset.StandardCharsets.UTF_8;
-import static java.util.Collections.unmodifiableList;
-import static java.util.Objects.requireNonNullElse;
-import static org.apache.commons.lang3.StringUtils.defaultString;
-
 @ParametersAreNonnullByDefault
 public class PlayHandler extends SimpleChannelInboundHandler<FullHttpRequest> {
     private static final Logger logger = LoggerFactory.getLogger(PlayHandler.class);
@@ -301,7 +299,7 @@ private void saveExceededSizeError(FullHttpRequest nettyRequest, Request request
                 error.append(":");
                 String size;
                 try {
-                    size = JavaExtensions.formatSize(Long.parseLong(length));
+                    size = Utils.formatSize(Long.parseLong(length));
                 } catch (Exception e) {
                     size = length + " bytes";
                 }
@@ -566,13 +564,13 @@ private void serve404(NotFound e, ChannelHandlerContext ctx, Request request) {
         FullHttpResponse nettyResponse = createHttpResponse(HttpResponseStatus.NOT_FOUND);
         nettyResponse.headers().set(CONTENT_TYPE, contentType);
 
-        String errorHtml = serverHelper.generateNotFoundResponse(request, format, e);
-        printResponse(ctx, nettyResponse, errorHtml);
+        String errorBody = serverHelper.generateErrorResponse(request, format, e, Response.current().encoding);
+        printResponse(ctx, nettyResponse, errorBody);
         logger.trace("serve404: end");
     }
 
-    private void printResponse(ChannelHandlerContext ctx, FullHttpResponse nettyResponse, String errorHtml) {
-        byte[] bytes = errorHtml.getBytes(Response.current().encoding);
+    private void printResponse(ChannelHandlerContext ctx, FullHttpResponse nettyResponse, String errorBody) {
+        byte[] bytes = errorBody.getBytes(Response.current().encoding);
         ByteBuf buf = ctx.alloc().buffer(bytes.length).writeBytes(bytes);
         setContentLength(nettyResponse, bytes.length);
         nettyResponse = nettyResponse.replace(buf);
@@ -591,7 +589,7 @@ private void serve500(Exception e, ChannelHandlerContext ctx, Request request, R
             String format = requireNonNullElse(request.format, "txt");
             nettyResponse.headers().set("Content-Type", MimeTypes.getContentType("500." + format, "text/plain"));
             try {
-                String errorHtml = serverHelper.generateErrorResponse(request, format, e);
+                String errorHtml = serverHelper.generateErrorResponse(request, format, e, Response.current().encoding);
 
                 byte[] bytes = errorHtml.getBytes(encoding);
                 ByteBuf buf = Unpooled.copiedBuffer(bytes);
diff --git a/replay-tests/criminals/app/criminals/Application.java b/replay-tests/criminals/app/criminals/Application.java
index 0f8b0cd3..160b8668 100644
--- a/replay-tests/criminals/app/criminals/Application.java
+++ b/replay-tests/criminals/app/criminals/Application.java
@@ -1,6 +1,9 @@
 package criminals;
 
+import play.PropertiesConfLoader;
+import play.TemplateErrorHandler;
 import play.modules.guice.GuiceBeanSource;
+import play.mvc.CookieSessionStore;
 import play.server.Starter;
 
 import javax.annotation.Nullable;
@@ -19,7 +22,7 @@ public int start(String playId, @Nullable String criminalRecordsServiceUrl) {
       configuration.setProperty("criminal-records.service.url", criminalRecordsServiceUrl);
     }
     GuiceBeanSource guice = new GuiceBeanSource(new Module(configuration));
-    return Starter.start(playId, guice);
+    return Starter.start(playId, new PropertiesConfLoader(), guice, new CookieSessionStore(), new TemplateErrorHandler());
   }
 
   public static void main(String[] args) {
diff --git a/replay-tests/helloworld/app/HelloWorldApp.java b/replay-tests/helloworld/app/HelloWorldApp.java
deleted file mode 100644
index 7b38cf7b..00000000
--- a/replay-tests/helloworld/app/HelloWorldApp.java
+++ /dev/null
@@ -1,11 +0,0 @@
-import play.server.Starter;
-
-public class HelloWorldApp {
-  public static void main(String[] args) {
-    int port = Starter.start("prod");
-
-    System.out.println("Try: http://localhost:" + port);
-    System.out.println("Try: http://localhost:" + port + "/public/hello_world.txt");
-    System.out.println();
-  }
-}
diff --git a/replay-tests/helloworld/app/hello/plugins/PlainTextTemplate.java b/replay-tests/helloworld/app/hello/plugins/PlainTextTemplate.java
index 7270cdcd..133c0cbf 100644
--- a/replay-tests/helloworld/app/hello/plugins/PlainTextTemplate.java
+++ b/replay-tests/helloworld/app/hello/plugins/PlainTextTemplate.java
@@ -20,7 +20,7 @@ public void compile() {
   }
 
   @Override
-  protected String internalRender(Map<String, Object> args) {
+  public String internalRender(Map<String, Object> args) {
     String result = contentAsString(source);
     for (Map.Entry<String, Object> arg : args.entrySet()) {
       result = result.replace("${" + arg.getKey() + "}", arg.getValue().toString());
diff --git a/replay-tests/helloworld/app/main/HelloWorldApp.java b/replay-tests/helloworld/app/main/HelloWorldApp.java
new file mode 100644
index 00000000..d674df94
--- /dev/null
+++ b/replay-tests/helloworld/app/main/HelloWorldApp.java
@@ -0,0 +1,28 @@
+package main;
+
+import play.PropertiesConfLoader;
+import play.TemplateErrorHandler;
+import play.SimpleErrorHandler;
+import play.inject.DefaultBeanSource;
+import play.mvc.CookieSessionStore;
+import play.server.Starter;
+
+public class HelloWorldApp {
+
+  public static void main(String[] args) {
+    int port = startWithTemplateErrorHandler("prod");
+    System.out.println("Try: http://localhost:" + port);
+    System.out.println("Try: http://localhost:" + port + "/public/hello_world.txt");
+    System.out.println();
+  }
+
+  public static int startWithTemplateErrorHandler(String playId) {
+    return Starter.start(playId, new PropertiesConfLoader(), new DefaultBeanSource(),
+        new CookieSessionStore(), new TemplateErrorHandler());
+  }
+
+  public static int startWithTextErrorHandler(String playId) {
+    return Starter.start(playId, new PropertiesConfLoader(), new DefaultBeanSource(),
+        new CookieSessionStore(), new SimpleErrorHandler());
+  }
+}
diff --git a/replay-tests/helloworld/test/ui/hello/HelloPdfWorldSpec.java b/replay-tests/helloworld/test/ui/hello/HelloPdfWorldSpec.java
index 8c3765dc..0e27bb44 100644
--- a/replay-tests/helloworld/test/ui/hello/HelloPdfWorldSpec.java
+++ b/replay-tests/helloworld/test/ui/hello/HelloPdfWorldSpec.java
@@ -9,7 +9,7 @@
 
 import static com.codeborne.pdftest.assertj.Assertions.assertThat;
 
-public class HelloPdfWorldSpec extends BaseSpec {
+public class HelloPdfWorldSpec extends TemplateErrorHandlerBaseSpec {
   @Test
   public void downloadHelloWorldPdf() throws IOException {
     PDF pdf = new PDF(new URL(Configuration.baseUrl + "/pdf"));
diff --git a/replay-tests/helloworld/test/ui/hello/HelloWorldSpec.java b/replay-tests/helloworld/test/ui/hello/HelloWorldSpec.java
index 68d8c1b2..fb9ab785 100644
--- a/replay-tests/helloworld/test/ui/hello/HelloWorldSpec.java
+++ b/replay-tests/helloworld/test/ui/hello/HelloWorldSpec.java
@@ -6,7 +6,7 @@
 import static com.codeborne.selenide.Selenide.$;
 import static com.codeborne.selenide.Selenide.open;
 
-public class HelloWorldSpec extends BaseSpec {
+public class HelloWorldSpec extends TemplateErrorHandlerBaseSpec {
   @Test
   public void openHelloWorldPage() {
     open("/");
diff --git a/replay-tests/helloworld/test/ui/hello/HttpSimpleErrorResponsesSpec.java b/replay-tests/helloworld/test/ui/hello/HttpSimpleErrorResponsesSpec.java
new file mode 100644
index 00000000..0b5529ad
--- /dev/null
+++ b/replay-tests/helloworld/test/ui/hello/HttpSimpleErrorResponsesSpec.java
@@ -0,0 +1,121 @@
+package ui.hello;
+
+import static io.restassured.RestAssured.given;
+import static io.restassured.RestAssured.when;
+import static java.nio.charset.StandardCharsets.UTF_8;
+import static java.util.Objects.requireNonNull;
+import static org.apache.commons.io.IOUtils.toByteArray;
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.hamcrest.Matchers.containsString;
+import static org.hamcrest.Matchers.equalTo;
+import static org.hamcrest.Matchers.notNullValue;
+import static org.hamcrest.Matchers.nullValue;
+
+import io.restassured.filter.log.LogDetail;
+import io.restassured.response.Response;
+import java.io.IOException;
+import org.apache.commons.io.IOUtils;
+import org.junit.jupiter.api.Test;
+
+/**
+ * Similar to the error response tests in HttpResponsesSpec but with the TextErrorHandler
+ */
+public class HttpSimpleErrorResponsesSpec extends SimpleErrorHandlerBaseSpec {
+
+  @Test
+  public void openMissingStaticFilePlain() {
+    given()
+        .header("Accept", "text/plain")
+        .when()
+        .get("/public/goodbye_world.jpeg")
+        .then()
+        .log().ifValidationFails(LogDetail.ALL)
+        .statusCode(404)
+        .header("Content-Length", Integer::parseInt, equalTo(64))
+        .header("Cache-Control", nullValue())
+        .header("accept-ranges", nullValue())
+        .header("Last-Modified", nullValue())
+        .header("ETag", nullValue())
+        .contentType("text/plain; charset=UTF-8")
+        .body(containsString("The file app/public/goodbye_world.jpeg does not exist"));
+  }
+
+  @Test
+  public void openMissingStaticFileHtml() {
+    given()
+        .header("Accept", "text/html")
+        .when()
+        .get("/public/goodbye_world.jpeg")
+        .then()
+        .log().ifValidationFails(LogDetail.ALL)
+        .statusCode(404)
+        .header("Content-Length", Integer::parseInt, equalTo(223))
+        .header("Cache-Control", nullValue())
+        .header("accept-ranges", nullValue())
+        .header("Last-Modified", nullValue())
+        .header("ETag", nullValue())
+        .contentType("text/html; charset=UTF-8")
+        .body(containsString("The file app/public/goodbye_world.jpeg does not exist"));
+  }
+
+  @Test
+  public void notFoundPlain() throws IOException {
+    Response response = given()
+        .header("Accept", "text/plain")
+        .when()
+        .get("/void");
+    response.then()
+        .log().ifValidationFails(LogDetail.ALL)
+        .statusCode(404)
+        .contentType("text/plain");
+    response.then()
+        .header("Content-Length", Integer::parseInt, equalTo(20));
+  }
+
+  @Test
+  public void notFoundHtml() throws IOException {
+    Response response = when()
+        .get("/void");
+    response.then()
+        .log().ifValidationFails(LogDetail.ALL)
+        .statusCode(404)
+        .contentType("text/html");
+    assertThat(response.body().asString()).isEqualToIgnoringWhitespace(
+        IOUtils.toString(requireNonNull(getClass().getResourceAsStream("not-found-simple.html")), UTF_8));
+    response.then()
+        .header("Content-Length", Integer::parseInt, equalTo(179));
+  }
+
+  @Test
+  public void badRequest() {
+    Response response = when().get("/repeat?times=zopa");
+    response.then().log().ifValidationFails(LogDetail.ALL).statusCode(400)
+        .header("Content-Length", Integer::parseInt, equalTo(210))
+        .contentType("text/html");
+    assertThat(response.body().asString()).contains("<p>[validation.invalid, validation.min]</p>");
+  }
+
+  @Test
+  public void serverError() throws IOException {
+    Response response = when()
+        .get("/epic-fail");
+    response.then()
+        .log().ifValidationFails(LogDetail.ALL)
+        .statusCode(500)
+        .header("Content-Length", Integer::parseInt, equalTo(175))
+        .contentType("text/html");
+    assertThat(response.body().asString()).isEqualToIgnoringWhitespace(
+        IOUtils.toString(requireNonNull(getClass().getResourceAsStream("server-error-simple.html")),
+            UTF_8));
+  }
+
+  @Test
+  public void notFound() {
+    Response response = when()
+        .get("/non-existing-path");
+    response.then()
+        .log().ifValidationFails(LogDetail.ALL)
+        .statusCode(404)
+        .header("Content-Length", Integer::parseInt, equalTo(192)).contentType("text/html");
+  }
+}
diff --git a/replay-tests/helloworld/test/ui/hello/HttpResponsesSpec.java b/replay-tests/helloworld/test/ui/hello/HttpTemplateResponsesSpec.java
similarity index 80%
rename from replay-tests/helloworld/test/ui/hello/HttpResponsesSpec.java
rename to replay-tests/helloworld/test/ui/hello/HttpTemplateResponsesSpec.java
index 064c3c1d..4b0e1dc8 100644
--- a/replay-tests/helloworld/test/ui/hello/HttpResponsesSpec.java
+++ b/replay-tests/helloworld/test/ui/hello/HttpTemplateResponsesSpec.java
@@ -18,7 +18,7 @@
 import static org.hamcrest.Matchers.notNullValue;
 import static org.hamcrest.Matchers.nullValue;
 
-public class HttpResponsesSpec extends BaseSpec {
+public class HttpTemplateResponsesSpec extends TemplateErrorHandlerBaseSpec {
   
   @RepeatedTest(100)
   public void openStaticFile() {
@@ -43,7 +43,7 @@ public void openMissingStaticFile() {
       then().
       log().ifValidationFails(LogDetail.ALL).
       statusCode(404).
-      header("Content-Length", Integer::parseInt, equalTo(511)).
+      header("Content-Length", Integer::parseInt, equalTo(223)).
       header("Cache-Control", nullValue()).
       header("accept-ranges", nullValue()).
       header("Last-Modified", nullValue()).
@@ -81,9 +81,9 @@ public void notFoundPage() throws IOException {
       statusCode(404).
       contentType("text/html");
     assertThat(response.body().asString()).isEqualToIgnoringWhitespace(
-      IOUtils.toString(requireNonNull(getClass().getResourceAsStream("not-found.html")), UTF_8)
+      IOUtils.toString(requireNonNull(getClass().getResourceAsStream("not-found-template.html")), UTF_8)
     );
-    response.then().header("Content-Length", Integer::parseInt, equalTo(467));
+    response.then().header("Content-Length", Integer::parseInt, equalTo(179));
   }
 
   @Test
@@ -94,10 +94,13 @@ public void badRequest() {
       then().
       log().ifValidationFails(LogDetail.ALL).
       statusCode(400).
-      header("Content-Length", Integer::parseInt, equalTo(45)).
+      header("Content-Length", Integer::parseInt, equalTo(25)).
       contentType("text/html");
     assertThat(response.body().asString()).isEqualToIgnoringWhitespace(
-      "<h1>[validation.invalid, validation.min]</h1>"
+      // When running the application we do get:
+      //    "<h1>[validation.invalid, validation.min]</h1>"
+      // When ui-test'ing the application we only get:
+            "<h1>[validation.min]</h1>"
     );
   }
 
@@ -109,11 +112,22 @@ public void serverError() throws IOException {
       then().
       log().ifValidationFails(LogDetail.ALL).
       statusCode(500).
-      header("Content-Length", Integer::parseInt, equalTo(267)).
+      header("Content-Length", Integer::parseInt, equalTo(245)).
       contentType("text/html");
     assertThat(response.body().asString()).isEqualToIgnoringWhitespace(
-      IOUtils.toString(requireNonNull(getClass().getResourceAsStream("server-error.html")), UTF_8)
+      IOUtils.toString(requireNonNull(getClass().getResourceAsStream("server-error-template.html")), UTF_8)
     );
   }
 
+  @Test
+  public void notFound() {
+    Response response = when().
+        get("/non-existing-path");
+    response.
+        then().
+        log().ifValidationFails(LogDetail.ALL).
+        statusCode(404).
+        header("Content-Length", Integer::parseInt, equalTo(192)).
+        contentType("text/html");
+  }
 }
diff --git a/replay-tests/helloworld/test/ui/hello/LargePostBodySpec.java b/replay-tests/helloworld/test/ui/hello/LargePostBodySpec.java
index e36488b0..2734ff91 100644
--- a/replay-tests/helloworld/test/ui/hello/LargePostBodySpec.java
+++ b/replay-tests/helloworld/test/ui/hello/LargePostBodySpec.java
@@ -10,7 +10,7 @@
 
 import static org.assertj.core.api.Assertions.assertThat;
 
-public class LargePostBodySpec extends BaseSpec {
+public class LargePostBodySpec extends TemplateErrorHandlerBaseSpec {
 
   @Test
   public void exerciseFileChannelBufferWithLargePostBody() {
diff --git a/replay-tests/helloworld/test/ui/hello/RenderStaticFilesSpec.java b/replay-tests/helloworld/test/ui/hello/RenderStaticFilesSpec.java
index 5c3d08d9..2ceb5419 100644
--- a/replay-tests/helloworld/test/ui/hello/RenderStaticFilesSpec.java
+++ b/replay-tests/helloworld/test/ui/hello/RenderStaticFilesSpec.java
@@ -16,7 +16,7 @@
 import static org.apache.commons.io.IOUtils.toByteArray;
 import static org.assertj.core.api.Assertions.assertThat;
 
-public class RenderStaticFilesSpec extends BaseSpec {
+public class RenderStaticFilesSpec extends TemplateErrorHandlerBaseSpec {
   @Test
   public void loadsBigImages() {
     open("/");
diff --git a/replay-tests/helloworld/test/ui/hello/BaseSpec.java b/replay-tests/helloworld/test/ui/hello/SimpleErrorHandlerBaseSpec.java
similarity index 85%
rename from replay-tests/helloworld/test/ui/hello/BaseSpec.java
rename to replay-tests/helloworld/test/ui/hello/SimpleErrorHandlerBaseSpec.java
index 78d76ada..7ab62e9a 100644
--- a/replay-tests/helloworld/test/ui/hello/BaseSpec.java
+++ b/replay-tests/helloworld/test/ui/hello/SimpleErrorHandlerBaseSpec.java
@@ -2,13 +2,12 @@
 
 import com.codeborne.selenide.Configuration;
 import io.restassured.RestAssured;
+import java.util.concurrent.atomic.AtomicBoolean;
+import main.HelloWorldApp;
 import org.junit.jupiter.api.BeforeEach;
 import play.Play;
-import play.server.Starter;
-
-import java.util.concurrent.atomic.AtomicBoolean;
 
-public class BaseSpec {
+public class SimpleErrorHandlerBaseSpec {
   private static final AtomicBoolean appStarted = new AtomicBoolean(false);
 
   @BeforeEach
@@ -21,7 +20,7 @@ public void setUp() {
   private static synchronized void startApp() {
     if (appStarted.get()) return;
 
-    int port = Starter.start("test");
+    int port = HelloWorldApp.startWithTextErrorHandler("test");
 
     Configuration.baseUrl = "http://localhost:" + port;
     Play.configuration.setProperty("application.baseUrl", Configuration.baseUrl);
diff --git a/replay-tests/helloworld/test/ui/hello/TemplateErrorHandlerBaseSpec.java b/replay-tests/helloworld/test/ui/hello/TemplateErrorHandlerBaseSpec.java
new file mode 100644
index 00000000..1bb14852
--- /dev/null
+++ b/replay-tests/helloworld/test/ui/hello/TemplateErrorHandlerBaseSpec.java
@@ -0,0 +1,33 @@
+package ui.hello;
+
+import com.codeborne.selenide.Configuration;
+import io.restassured.RestAssured;
+import org.junit.jupiter.api.BeforeEach;
+import play.Play;
+import main.HelloWorldApp;
+
+import java.util.concurrent.atomic.AtomicBoolean;
+
+public class TemplateErrorHandlerBaseSpec {
+  private static final AtomicBoolean appStarted = new AtomicBoolean(false);
+
+  @BeforeEach
+  public void setUp() {
+    System.setProperty("webdriver.http.factory", "jdk-http-client");
+    if (appStarted.get()) return;
+    startApp();
+  }
+
+  private static synchronized void startApp() {
+    if (appStarted.get()) return;
+
+    int port = HelloWorldApp.startWithTemplateErrorHandler("test");
+
+    Configuration.baseUrl = "http://localhost:" + port;
+    Play.configuration.setProperty("application.baseUrl", Configuration.baseUrl);
+
+    RestAssured.baseURI = Configuration.baseUrl;
+    RestAssured.port = port;
+    appStarted.set(true);
+  }
+}
diff --git a/replay-tests/helloworld/test/ui/hello/not-found-simple.html b/replay-tests/helloworld/test/ui/hello/not-found-simple.html
new file mode 100644
index 00000000..fb63ca85
--- /dev/null
+++ b/replay-tests/helloworld/test/ui/hello/not-found-simple.html
@@ -0,0 +1,11 @@
+<!doctype html>
+<html lang="en">
+<head>
+  <title>Not found</title>
+  <meta charset="UTF-8"/>
+</head>
+<body>
+<h1>Not found</h1>
+<p>GET /void</p>
+</body>
+</html>
\ No newline at end of file
diff --git a/replay-tests/helloworld/test/ui/hello/not-found-template.html b/replay-tests/helloworld/test/ui/hello/not-found-template.html
new file mode 100644
index 00000000..14416ccb
--- /dev/null
+++ b/replay-tests/helloworld/test/ui/hello/not-found-template.html
@@ -0,0 +1,11 @@
+<!doctype html>
+<html lang="en">
+  <head>
+    <title>Not found</title>
+    <meta charset="UTF-8"/>
+  </head>
+  <body>
+    <h1>Not found</h1>
+    <p>GET /void</p>
+  </body>
+</html>
\ No newline at end of file
diff --git a/replay-tests/helloworld/test/ui/hello/not-found.html b/replay-tests/helloworld/test/ui/hello/not-found.html
deleted file mode 100644
index 68072103..00000000
--- a/replay-tests/helloworld/test/ui/hello/not-found.html
+++ /dev/null
@@ -1,16 +0,0 @@
-<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
-<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
-<head>
-  <title>Not found</title>
-  <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/>
-</head>
-<body>
-
-
-<h1>Not found</h1>
-<p>
-  GET /void
-</p>
-
-</body>
-</html>
\ No newline at end of file
diff --git a/replay-tests/helloworld/test/ui/hello/server-error-simple.html b/replay-tests/helloworld/test/ui/hello/server-error-simple.html
new file mode 100644
index 00000000..eb424acc
--- /dev/null
+++ b/replay-tests/helloworld/test/ui/hello/server-error-simple.html
@@ -0,0 +1,10 @@
+<!doctype html>
+<html lang="en">
+<head>
+  <title>Server error</title>
+  <meta charset="UTF-8"/>
+</head>
+  <body>
+    <h1>Oops, an error occurred</h1>
+  </body>
+</html>
\ No newline at end of file
diff --git a/replay-tests/helloworld/test/ui/hello/server-error-template.html b/replay-tests/helloworld/test/ui/hello/server-error-template.html
new file mode 100644
index 00000000..46802d9c
--- /dev/null
+++ b/replay-tests/helloworld/test/ui/hello/server-error-template.html
@@ -0,0 +1,10 @@
+<!doctype html>
+<html lang="en">
+  <head>
+    <title>Application error</title>
+    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/>
+  </head>
+  <body>
+    <h1>Oops, an error occurred</h1>
+  </body>
+</html>
\ No newline at end of file
diff --git a/replay-tests/helloworld/test/ui/hello/server-error.html b/replay-tests/helloworld/test/ui/hello/server-error.html
deleted file mode 100644
index 08ed6a27..00000000
--- a/replay-tests/helloworld/test/ui/hello/server-error.html
+++ /dev/null
@@ -1,14 +0,0 @@
-<!DOCTYPE html>
-
-<html>
-<head>
-  <title>Application error</title>
-  <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/>
-</head>
-<body>
-
-
-<h1>Oops, an error occurred</h1>
-
-</body>
-</html>
\ No newline at end of file