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 ('61ce2eae4fcbd883f38f508e4818e518', -1, 1539950263, 1539950263, '36e11a2c', 6, 0, 0)

Line : 187
File : sessions.php