Warning: mysqli_connect(): (HY000/2002): No such file or directory in /home/tsvinfor/tsvinfo.ru/docs/inc/bases_s.inc on line 20

Warning: mysqli_error() expects exactly 1 parameter, 0 given in /home/tsvinfor/tsvinfo.ru/docs/inc/bases_s.inc on line 20
I cannot connect to the database because: