phpBB : Critical Error

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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 = '5bb7ce5c5c6fe14e78b523a967467c88' AND u.user_id = s.session_user_id

Line : 330
File : sessions.php