I had this problem for a couple of weeks. I tried everything mentioned here first, but had no luck.

I was uploading to a facebook album with "custom" permission, namely "friends of friends". (I had been doing this with no problem for ages).

Uploading to "mobile uploads" was ok, as was albums with non-custom permissions eg. "friends only".

Changing the permissions of my album to "friends only" fixed the problem for me.

I also found that facebook albums have a limit of 200 photos, but no limit on the number of albums you can have - this is buried in facebook's help pages.