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 ('3983bd6c43f1aa59de0b651acbbc5aea', -1, 1553545288, 1553545288, '22e42a19', 20, 0, 0)

Line : 187
File : sessions.php