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 ('e784621113b5cc0fdd7cff539f817f60', -1, 1539693297, 1539693297, '36e076f7', -11, 0, 0)

Line : 187
File : sessions.php