phpBB : Critical Error

Error creating new session

DEBUG MODE

SQL Error : 1062 Duplicate entry '-1' for key 'session_user_id'

INSERT INTO phpbb_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('c1677f84952b7d40cccfb8ec66bf3911', -1, 1413862903, 1413862903, '36a1e41d', -1, 0, 0)

Line : 187
File : sessions.php