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 ('a5392f44e37d9ac489d52a3974ddb097', -1, 1464083608, 1464083608, '36c6648d', 10014, 0, 0)

Line : 190
File : sessions.php