phpBB : Critical Error

Error creating new session

DEBUG MODE

SQL Error : 1062 Duplicate entry '-1' for key 'session_user_id'

INSERT INTO iabb_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('d8f82aaceb863ccdaff0a1f8f71f699d', -1, 1561069567, 1561069567, '3698269a', 33, 0, 0)

Line : 187
File : sessions.php