diff --git a/src/Maintenance.php b/src/Maintenance.php
index a84433b..9040ed9 100644
--- a/src/Maintenance.php
+++ b/src/Maintenance.php
@@ -165,7 +165,7 @@ public function executeCronJobs(): void
                 //add default callback settings if defined
                 if (($settings = $config->getExecutorSettings()) !== '' && ($settings = $config->getExecutorSettings()) !== '0') {
                     $settings = json_decode((string) $settings, true, 512, JSON_THROW_ON_ERROR);
-                    if (isset($settings['values']['defaultPreDefinedConfig'])) {
+                    if (isset($settings['values']['defaultPreDefinedConfig']) && is_int($settings['values']['defaultPreDefinedConfig'])) {
                         $preDefinedConfigId = $settings['values']['defaultPreDefinedConfig'];
                         $callbackSetting = CallbackSetting::getById($preDefinedConfigId);
                         if ($callbackSetting && ($v = $callbackSetting->getSettings())) {