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 ('f6c3b7b6bc7fb703e8c6af12635e1393', -1, 1534274456, 1534274456, '36c44916', 0, 0, 0)

Line : 189
File : sessions.php