PHPBB3 Not working since 2.9.1 upgrade

I have scoured the forums trying to find the solution to this problem but cannot find a solution.

I have a wordpress blog at https://www.mysite.com and a PHPBB3 forum at https://www.mysite.com/forum.

These both worked fine until upgrading to 2.9.1, now visiting the forum just gives me a database connection error. I have checked the details in both my configs and they agree with eachother.

Any help would be appreciated.