Like so damn many things in M$ products, it's a misleading message. It's not necessarily the filename, but it could be - the problem is the entire pathname is too long. You diod the best you could by renaming a folder.
This was a real problem in the early, early days of CD burning. Nero didn't like long pathname in the least, I can remember burning some work related CD's with my drivers, tool apps & manuals on them and having some tedious times going back and renaming stuff.