phpBB : Critical Error

Error doing DB query userdata row fetch

DEBUG MODE

SQL Error : 2006 MySQL server has gone away

SELECT u.*, s.* FROM phpbb_sessions s, phpbb_users u WHERE s.session_id = '96ae33d2f849f66c841e0509e68f9f29' AND u.user_id = s.session_user_id

Line : 267
File : sessions.php