phpBB : Critical Error

Error creating new session

DEBUG MODE

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

INSERT INTO forum_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('7a2964822947ba5c29e6b6b4f0c630f5', -1, 1540328876, 1540328876, '36e05922', 16, 0, 0)

Line : 187
File : sessions.php