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 ('6fe00755e8a67c7704855e765013d341', -1, 1492991218, 1492991218, '3651d0ad', 26, 0, 0)

Line : 172
File : sessions.php