phpBB : Critical Error

Error doing DB query userdata row fetch

DEBUG MODE

SQL Error : 2013 Lost connection to MySQL server during query

SELECT u.*, s.* FROM phpbb2_sessions s, phpbb2_users u WHERE s.session_id = '4fc2fa16f096e59f6a1cd52d4445b77e' AND u.user_id = s.session_user_id

Line : 315
File : sessions.php