The FogBugz database is down or could not be found.Edit the file application.data in the FogBugz/Accessories folder. Correct the line sConnectionString:Driver={mySQL};Server=data.domain.com;Database=my-database;Uid=username;Pwd=password
If you need to install FogBugz, visit http://localhost/FogBugz/install1.php from the FogBugz server.

Error: mysql error: [2002: Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2)] in CONNECT(localhost, '****', '****', fogbugz)

See this article for authentication problems.