Ohfer,
I'm running out, so I don't have time to test this, so I suggest this with the caveat that
you should absolutely make a copy of your league and test this fix with the copy!
Try deleting the faces.dat file from your saved game (with OOTP closed). Then restart the game, and try to make it cause that same error again (make it try to put a new cap/uniform on the picture of a player that had his face generated in OOTP8).
Let me know how that goes.
By the way, if you do this on your original league files without backing up first, I reserve the right to say "I told you so."
Steve