[phpBB Debug] PHP Warning: in file [ROOT]/common.php on line 105: Undefined variable $sql_db

Fatal error: Uncaught Error: Class name must be a valid object or a string in D:\inetpub\webs\blue-areanet\public\phpBB3\common.php:105 Stack trace: #0 D:\inetpub\webs\blue-areanet\public\phpBB3\ucp.php(17): require() #1 {main} thrown in D:\inetpub\webs\blue-areanet\public\phpBB3\common.php on line 105