diff --git a/src/copy.ml b/src/copy.ml
index 9ab9314eb..a3c1afc49 100644
--- a/src/copy.ml
+++ b/src/copy.ml
@@ -168,7 +168,7 @@ let rec fingerprintPrefix fspath path offset len accu =
   end
 
 let fingerprintPrefixRemotely =
-  Remote.registerServerCmd
+  Remote.registerRemoteCmd
     "fingerprintSubfile"
     Umarshal.(prod3 Fspath.m Path.mlocal Uutil.Filesize.m id id)
     Umarshal.(list Fingerprint.m)
@@ -382,7 +382,7 @@ let loadPropsExtDataLocal (fspath, path, desc) =
     | `Global p -> Update.translatePathLocal fspath p in
   (Some localPath, Props.loadExtData fspath localPath desc)
 
-let loadPropsExtDataOnServer = Remote.registerServerCmd "propsExtData"
+let loadPropsExtDataOnServer = Remote.registerRemoteCmd "propsExtData"
   Umarshal.(prod3 Fspath.m mxpath Props.m id id)
   Umarshal.(prod2 (option Path.mlocal) Props.mx id id)
   (fun connFrom args -> Lwt.return (loadPropsExtDataLocal args))
@@ -638,7 +638,7 @@ let convV0 = Remote.makeConvV0FunArg
        ((biOpt, fspathFrom, pathFrom, fileKind), (sizeFrom, id, file_id)))
 
 let compressRemotely =
-  Remote.registerServerCmd "compress" ~convV0 mcompress Umarshal.unit compress
+  Remote.registerRemoteCmd "compress" ~convV0 mcompress Umarshal.unit compress
 
 let close_all infd outfd =
   Util.convertUnixErrorsToTransient
@@ -1181,17 +1181,10 @@ let file rootFrom pathFrom rootTo fspathTo pathTo realPathTo
       (Fspath.toDebugString fspathTo) (Path.toString pathTo)
       (Props.toString desc));
   let timer = Trace.startTimer "Transmitting file" in
-  begin match rootFrom, rootTo with
-    (Common.Local, fspathFrom), (Common.Local, realFspathTo) ->
-      localFile
-        fspathFrom pathFrom fspathTo pathTo realPathTo
-        update desc (Osx.ressLength ress) (Some id);
-        paranoidCheck fspathTo pathTo realPathTo desc fp ress
-  | _ ->
-      transferFile
-        rootFrom pathFrom rootTo fspathTo pathTo realPathTo
-        update desc fp ress id
-  end >>= fun status ->
+  transferFile
+    rootFrom pathFrom rootTo fspathTo pathTo realPathTo
+    update desc fp ress id
+  >>= fun status ->
   Trace.showTimer timer;
   match status with
     TransferSucceeded info ->
diff --git a/src/remote.ml b/src/remote.ml
index 1439da367..19bc71fc8 100644
--- a/src/remote.ml
+++ b/src/remote.ml
@@ -423,7 +423,9 @@ let connectionIO conn =
 let setConnectionVersion conn ver =
   conn.version <- ver
 
-let connectionVersion conn = conn.version
+let connectionVersion = function
+  | None -> rpcDefaultVersion
+  | Some conn -> conn.version
 
 let connEq conn conn' =
   conn.inputBuffer.channel = conn'.inputBuffer.channel
@@ -596,7 +598,12 @@ module ClientConn = struct
 
 end (* module ClientConn *)
 
-let connectionOfRoot root = ClientConn.ofRoot root
+let connectionOfRoot root =
+  (* This is not the same as [ClientConn.ofRootOpt]. We want this function
+     to fail when the remote connection is not found. *)
+  match root with
+  | (Common.Local, _) -> None
+  | (Common.Remote _ , _) -> Some (ClientConn.ofRoot root)
 
 (****)
 
@@ -1141,6 +1148,17 @@ let registerServerCmd name ?(convV0=convV0_id_pair) mArg mRet f =
     name (defaultMarshalingFunctions (fst convV0) mArg)
          (defaultMarshalingFunctions (snd convV0) mRet) f
 
+(* Same as [registerServerCmd] but returns a function that runs either
+   the proxy or the local version, depending on whether the call is to
+   the local host (in this case [conn] is None) or a remote one. *)
+let registerRemoteCmd name ?convV0 mArg mRet f =
+  let serverSide = (fun conn args -> f (Some conn) args) in
+  let client0 = registerServerCmd name ?convV0 mArg mRet serverSide in
+  fun conn args ->
+    match conn with
+    | None -> f None args
+    | Some conn -> client0 conn args
+
 (* RegisterHostCmd is a simpler version of registerClientServer [registerServerCmd?].
    It is used to create remote procedure calls: the only communication
    between the client and server is the sending of arguments from
@@ -1174,16 +1192,15 @@ let registerRootCmd (cmdName : string)
   fun root args -> r root ((snd root), args)
 
 let registerRootCmdWithConnection (cmdName : string)
-  ?(convV0=convV0_id_pair) mArg mRet (cmd : connection -> 'a -> 'b) =
-  let client0 = registerServerCmd cmdName ~convV0 mArg mRet cmd in
+  ?(convV0=convV0_id_pair) mArg mRet (cmd : connection option -> 'a -> 'b) =
+  let serverSide = (fun conn args -> cmd (Some conn) args) in
+  let client0 = registerServerCmd cmdName ~convV0 mArg mRet serverSide in
   (* Return a function that runs either the proxy or the local version,
      depending on whether the call is to the local host or a remote one *)
   fun localRoot remoteRoot args ->
     match (fst localRoot) with
-    | Common.Local -> let conn = ClientConn.ofRoot remoteRoot in
-            cmd conn args
-    | _  -> let conn = ClientConn.ofRoot localRoot in
-            client0 conn args
+    | Common.Local -> cmd (connectionOfRoot remoteRoot) args
+    | _ -> client0 (ClientConn.ofRoot localRoot) args
 
 let streamReg = lwtRegionWithConnCleanup 1
 
@@ -1199,13 +1216,13 @@ let streamingActivated =
 let registerStreamCmd
     (cmdName : string)
     marshalingFunctionsArgs
-    (serverSide : connection -> 'a -> unit)
+    (serverSide : connection option -> 'a -> unit)
     =
   let cmd =
     registerSpecialServerCmd
       cmdName marshalingFunctionsArgs
       (defaultMarshalingFunctions convV0_id Umarshal.unit)
-      (fun conn v -> serverSide conn v; Lwt.return ())
+      (fun conn v -> serverSide (Some conn) v; Lwt.return ())
   in
   let ping =
     registerServerCmd (cmdName ^ "Ping") Umarshal.int Umarshal.unit
@@ -1227,7 +1244,7 @@ let registerStreamCmd
   (* Create a server function and remember it *)
   let server conn buf =
     let args = unmarshalArgs conn buf in
-    serverSide conn args
+    serverSide (Some conn) args
   in
   serverStreams := Util.StringMap.add cmdName server !serverStreams;
   (* Create a client function and return it *)
@@ -1240,7 +1257,7 @@ let registerStreamCmd
     in
     dumpIdle conn request
   in
-  fun conn sender ->
+  let proxy conn sender =
     if not (Prefs.read streamingActivated) then
       sender (fun v -> cmd conn v)
     else begin
@@ -1259,6 +1276,11 @@ let registerStreamCmd
            end else
              Lwt.fail e)
     end
+  in
+  fun conn sender ->
+    match conn with
+    | None -> sender (fun v -> Lwt.return (serverSide conn v))
+    | Some conn -> proxy conn sender
 
 let commandAvailable =
   registerRootCmd "commandAvailable" Umarshal.string Umarshal.bool
diff --git a/src/remote.mli b/src/remote.mli
index 8c7ec22a3..b9565f0b5 100644
--- a/src/remote.mli
+++ b/src/remote.mli
@@ -126,15 +126,18 @@ module MsgIdMap : Map.S with type key = msgId
 val newMsgId : unit -> msgId
 
 type connection
-val connectionVersion : connection -> int
-val connectionOfRoot : Common.root -> connection
+val connectionVersion : connection option -> int
+val connectionOfRoot : Common.root -> connection option
+(* [connectionOfRoot] is None for a local root,
+   Some connection for a remote root,
+   raises if a remote connection is not found. *)
 
-val registerServerCmd :
+val registerRemoteCmd :
   string
  -> ?convV0: 'a convV0Fun * 'b convV0Fun
  -> 'a Umarshal.t -> 'b Umarshal.t
- -> (connection -> 'a -> 'b Lwt.t)
- -> connection -> 'a -> 'b Lwt.t
+ -> (connection option -> 'a -> 'b Lwt.t)
+ -> connection option -> 'a -> 'b Lwt.t
 val intSize : int
 val encodeInt : int -> Bytearray.t * int * int
 val decodeInt : Bytearray.t -> int -> int
@@ -144,7 +147,7 @@ val registerRootCmdWithConnection :
                                     (* 2.51-compatibility functions for args
                                        and result *)
  -> 'a Umarshal.t -> 'b Umarshal.t
- -> (connection -> 'a -> 'b Lwt.t)  (* local command *)
+ -> (connection option -> 'a -> 'b Lwt.t)  (* local command *)
  ->    Common.root                  (* root on which the command is executed *)
     -> Common.root                  (* other root *)
     -> 'a                           (* additional arguments *)
@@ -157,8 +160,8 @@ val registerStreamCmd :
   (connection -> 'a ->
    (Bytearray.t * int * int) list -> (Bytearray.t * int * int) list * int) *
   (connection -> Bytearray.t -> int -> 'a) ->
-  (connection -> 'a -> unit) ->
-  connection -> (('a -> unit Lwt.t) -> 'b Lwt.t) -> 'b Lwt.t
+  (connection option -> 'a -> unit) ->
+  connection option -> (('a -> unit Lwt.t) -> 'b Lwt.t) -> 'b Lwt.t
 
 (* Register a function to be run when the connection between client and server
    is closed (willingly or unexpectedly). The function should not raise