So, I uploaded my PHPBB files to my site (after a server crash) and i forgot to set permissions to /store /files /cache / and images/avatars/upload/
so in my admin pannel i got a error at the bottom that /cache/ wasnt writeble, so i fixed that part.

then I went to update my board from .4 to .5, with still a few directories without write.

so i got to the part of "checking files" and it just stayed on 30 files.. kept reloading but no files were added to the number (and i didn't get a error!)

And the "Test out user’s permissions" also didn't work (and again no error) it said it changed the permissions but nothing changed.

so to figure out what the problem was i uploaded a .5 clean to another dir and got the "not writable" errors during the setup, so i changed the permissions on my primary install, and the update continued, and was successful.

and also the "Test out user’s permissions" worked again.

so maybe some file checking would be in order (ether in the update, and/or in the admin pannel for /store /files /images/avatars/upload/ ?)

(Server: Unix, CentOS)
Hope this helps.
Zero.