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 ('45c99a27a5c64df7fcbf255add39ca39', -1, 1540147369, 1540147369, '3691534f', 2, 0, 0)

Line : 187
File : sessions.php