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 ('f6610ae37af978a30e1ad8e153051503', -1, 1467366533, 1467366533, '369ed119', -4, 0, 0)

Line : 201
File : sessions.php