Error when accessing the forum

[pwadm]

This is an existing installation, with no changes made in the last few weeks. When I try to access the main page or the admin.php I am getting this generic error. The html page doesn't contain anything else (I checked the source):

An unexpected error occurred. Please try again later.

How can I troubleshoot? Apache is running as I can access other files on the server. I also checked apache, and mysql logs, but don't see anything.

Is there a XenForo specific log file where I can look for an explanation?

 

[pwadm]

What I did is enabled 'debug' mode in the config.php file, and then accessed admindav.php, which showed me the error. Memcached stopped working for some reason, and since it was configured for the forum, the forum stopped working as well.

 

[sonnb]

This error related do database. Check your database information or connection. Restart database service might help.