Piwigo encountered a non recoverable error

[mysql error 2002] Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (111 "Connection refused")
Can't connect to server

#1	my_error /var/www/vhosts/tribalfusion.es/httpdocs/fotos/include/common.inc.php(128)
#2	include_once /var/www/vhosts/tribalfusion.es/httpdocs/fotos/index.php(26)