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) VALUES ('a2b7494f01456c51fd28f9c7c4ffc431', -1, 1490611285, 1490611285, 'ac444111', 14, 0)

Line : 158
File : sessions.php