The advice given here beforehand to copy the attachments and avatars etc was done before I started the upgrade.
I have copied the files back to the same locations, but the forum is not seeing them.
I did go into my own profile, and could see the image, but when I went to click save, it said it could not upload it.
I am using the default theme.
The folders for avatars , attachments etc is under /forums
I could only find one reference to the same issue here on this forum, but it was never updated with a resolution.

I have rebuilt the custom avatars in the Maintenance section without any success.