How to fix Folder Redirection Event 502 - The Network Path Was Not Found - Failed to Redirect Because Offline
Folder Redirection Event 502 - Failed to redirect because the destination directory '\\server\redirecteddocs$\username\My Documents' is offline. Error details: The network path was not found.
You probably noticed this error because you are trying to change the path of your existing redirected documents. You may have configured a new group policy that points to a new share, or you may be removing a user from a group policy, so their documents will go back to the local paths. Or it the redirected documents may have broke at some point, and you are troubleshooting the issue.
There are a few things that can cause this error. First, the path the error is referencing may actually be offline. From the file server, check that the share is still working correctly. Secondly, there may be a permission misconfiguration on the users redirected folder. Go to the file server and make sure the user has the correct permissions on their folder. Here is the microsoft article on security permissions for redirected documents. Reference it if you need to. It's for new setups, but has good information in it. For this situation, at least make sure the user has full control over their folder, and it's shared properly.
Most likely, you have already tried these steps, and the issue is still there. If that's the case, 99% of the time, it's a CSC cache issue. No problem, reinitializing the cache will solve this. I suggest making a backup of the documents from the workstation before doing this. If there is an issue with the CSC cache, it's possible that the files haven't synced with the file server recently.
So basically, backup the files from the workstation, run the Fix It utility, and reboot. This should fix the issue.