I update 1.21.3 to 1.22.0. I have set the socket of mysql to another file. But the 1.22.0 must use /var/lib/mysql/mysql.sock to access the DB. I create a symbol link file to link my socket. "php update.php" is OK. But the website still says that can not access DB.
Topic on Project:Support desk
Maybe related to switching from using mysql to mysqli for db access.
If you currently have $wgDBServer set to localhost, changing it to be 127.0.0.1 can force php to use the network instead of a local sock.
In php.ini, I also set the mysqli.default_socket to my socket file. Then it's ok now.