phpBB : 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 ('36459fe1eff54b57b9a946fe9f77a3a2', -1, 1542753479, 1542753479, '36a75f33', 0, 0, 0)

Line : 187
File : sessions.php