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 ('da93360b0bf9c3ed25629f0ea38cbd97', -1, 1539804575, 1539804575, '36a6cfdf', 4, 0, 0)

Line : 187
File : sessions.php