If you happened to have file-name or folder-path greater than 255 characters, it is time to review it and make sure it does not exceed 255 characters. This is what happen:-
A client of mine was backing up their disk/folder/files with a reputable backup solution. Backup was completed with warning(s) (well, error – particularly for this folder-path greater than 255 characters) stating the folder cannot be successfully backed up. The rest are backed up and written to the backup media (happened to be RDX media).
When they want to restore the backed up data, it failed for no given reason. They have spent 3 weeks trying to identify the restore failure and eventually found out that the folder-path is longer than the allowable 255 characters. It is a very expensive lesson for them as the one folder has caused the entire restore process to fail.