phpBB by Przemo : 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 ('d3671c5f4b9e0219d9bc5792ee8acffd', -1, 1540116943, 1540116943, '36a16418', -4, 0, 0)

Line : 445
File : sessions.php