I was enabling Folder Redirection for some Windows 7 Professional machines, or rather, for the users of some Windows 7 Professional machines. The users already had a server based home directory with a My Documents folder, which also had data. The purpose of the operation was to, firstly, enable Folder Redirectin, but also to merge the contents of the My Documents folder on the client machines with the My Documents folder on the network server. First, to see what kind of conflict resolution Folder Redirection had, I created a file with the same name (but different content) in both the local My Documents folder and the one on the server. After logging on the first time the Folder Redirection policy was active I found this error event in the Application log on the client machine:

Log Name:      Application
Source:        Microsoft-Windows-Folder Redirection
Event ID:      502
Level:         Error
User:          <domain><username>
Computer:      <computername>
Description: Failed to apply policy and redirect folder Documents to \<servername><share><username>Documents.
Redirection options=0x1001.
The following error occurred: Failed to copy files from C:Users<username>Documents to  \<servername><share><username>Documents.
Error details: This function is not supported on this system.

Originally I thought this was a problem with NTFS file permissions on the file server, but these we OK. After all, other clients were redirecting their folders without problem. Since the error details didn’t give me any clue I decided to try to remove my offending duplicate file. I deleted it from the client machine and on the next logon the My Documents folder redirected without problem.

The error in the log should have a better explanation of what is happening. Folder Redirection is definitely supported on Windows 7 Professional. The Folder Redirection specific event logs didn’t contain any more information either. The error text should have said something along the lines “File conflict; file X already exists”. Maybe in Windows 8.

Unfortunately I solved the problem before I had a chance to enable debug logging for the Folder Redirection Client Side Extension. Maybe that would have told me what the problem was. Should you want to enable debug logging for Folder Redirection you can do so with this command:

reg.exe add “HKLMSoftwareMicrosoftWindows NTCurrentVersionDiagnostics” /v FdeployDebugLevel /d 0x0f /t REG_DWORD

If you are on Windows XP/2003 or earlier this will give you a log file: %windir%debugusermodefdeploy.log. If you are running Windows Vista/2008 or newer you will simply get more events in the Windows event logs.

So, should you find yourself staring at this error in the middle of the night (or any other time), see if you have any duplicate files in the folders you are trying to redirect.

Happy redirecting!

UPDATE: The duplicate files I created were created by a different account than the user owning the client computer and home directory on the server. That means that the user actually owning the folders could not delete or move the duplicate file. That could also be the reason for this error. But the fact remains; it is still a very poor error message.

UPDATE 2: I have now had a chance to test the conflict resolution in Folder Redirection and from my tests it seems that the client wins if the same file (but with different content) exists on both the server where you are redirecting to and on the client. I performed the same experiment as outlined above; two files with the same name, one on the server and one on the client. This time they were both created by the user owning the client and the folder on the server. Upon the next logon the folder redirection policy took effect and the local files were copied to the server, merging them with the content that already existed there. But as I say, the copy of the identical file on the server was silently overwritten by the file on the client. So now you know.