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 phpbb_sessions s, phpbb_users u WHERE s.session_id = 'f8ffa64119743dc9b12acdf8abae43fb' AND u.user_id = s.session_user_id

Line : 261
File : sessions.php