Warning: mysqli::mysqli(): (HY000/2002): Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (111) in /var/www/html/piwigo/include/dblayer/functions_mysqli.inc.php on line 52

Warning: my_error(): Couldn't fetch mysqli in /var/www/html/piwigo/include/dblayer/functions_mysqli.inc.php on line 848

Warning: my_error(): Couldn't fetch mysqli in /var/www/html/piwigo/include/dblayer/functions_mysqli.inc.php on line 848

Piwigo encountered a non recoverable error

[mysql error ] 
Can't connect to server

#1	my_error /var/www/html/piwigo/include/common.inc.php(113)
#2	include_once /var/www/html/piwigo/index.php(11)