phpBB : Critical Error

Error creating new session

DEBUG MODE

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

INSERT INTO r2ok_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('466e2ed94ffae51c5b84f0435fa9e6cf', -1, 1524206193, 1524206193, '3650082c', 33, 0, 0)

Line : 187
File : sessions.php