The source file name(s) are larger than is supported by the file system.

The source file name(s) are larger than is supported by the file system.  Try moving to a location which has a shorter path name, or try renaming to shorter name(s) before attempting this operation.

Recently I found that some operations in a backup maintenance job where failing because a file it was trying to remove was failing due to the filenames/path length.

I did the typical options available none of which worked:

• Attempt to rename it via cmd prompt
• Attempt to rename it via cmd prompt using the short name.  It contained several special characters and I never could figure out which one it was complaining about.
• Attempt to rename the directories containing it.  Even using a single letter for each directory didn't reduce it enough.

In the end a simple command did the trick to get the path short enough.

• Navigate into the directory in question
• subst M: . (notice the period there indicating current directory)
• del filename (or rename filename newfilename)
• subst M: /D