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 ('48006c3ba8324226c2aa70f75a9c1d7c', -1, 1513244980, 1513244980, '36a3d16d', 11, 0, 0)

Line : 192
File : sessions.php