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 ('86cf9c1c250910488c5d2f0c847a3f84', -1, 1539686347, 1539686347, '369ed0bd', -11, 0, 0)

Line : 187
File : sessions.php