Redirect folder redirection: "Failed to apply ... The filename or extension is too long."

I'm moving files from one server to another. The source server stores users' redirected folders. I have this set up with GPO filtering: If I make an account member in a specific group, a new set of Folder Redirection settings take effect, and is synchronized with another folder on destination server. This works well with my test accounts.

However, when I asked my "pilot" to log in, while the redirected folders (Desktop, Documents, etc) were created on the destination server, no files where transferred.

In the Event Viewer there's an Folder Redirection error 502. It says (and this is important because Google does not have many hits on this specific content of this event): "Failed to apply policy and redirect folder ... The filename or extension is too long."

(I don't bother to copy and paste the whole event because it is not in English.)

When I try to recreate this problem, I cannot, because Windows does not allow me to create folder structures where the file name or path gets too long.

I cannot easily investigate this particular user's folder structure, because he has exclusive rights on it and needs to have access to it continously.

Any hint or thought on how to attack this would be much appreciated.