phpBB : Critical Error

Error creating new session

DEBUG MODE

SQL Error : 1062 Duplicate entry '-1' for key 'phpbb_sessions.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 ('40b6e09a6dda400d2ab5599a49136499', -1, 1768186725, 1768186725, 'd849d897', -9, 0, 0)

Line : 187
File : sessions.php