Cannot empty trash (Unknown MySQL server host)
PermalinkSQLSTATE[HY000] [2005] Unknown MySQL server host 'localhost:9001' (2)
I guess the problem is that my MySQL server is on a different port than the default 3306? This seems weird, though, since the rest of the system works fine.
Any solution?

If you override the "pdo_mysql" with ",mysql", than works and has nothing to do with mysql Port :/
Standard code C 5.6.3
$type = 'pdo_mysql'; if (!extension_loaded('pdo_mysql')) { $type = 'mysql'; }
Update with:
$type = 'mysql'; if (!extension_loaded('pdo_mysql')) { $type = 'mysql'; }