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 ('4530694a3872cf2808fe028f57b85074', -1, 1513244699, 1513244699, '36a3d16d', 7, 0, 0)

Line : 192
File : sessions.php