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 ('6b3324d829ed8e8a605f04cc1653541c', -1, 1513298143, 1513298143, '36eaf776', 1, 0, 0)

Line : 189
File : sessions.php