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 ('a7872a9ceb8a76f340df8cf5056a5ef9', -1, 1561046773, 1561046773, '365b476c', 15, 0, 0)

Line : 187
File : sessions.php