phpBB : Critical Error

Error creating new session

DEBUG MODE

SQL Error : 1062 Duplicate entry '-1' for key 'session_user_id'

INSERT INTO forum_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('5b587b8f7111cc9c17f8c4a4f18b6bf8', -1, 1540227532, 1540227532, '36e0f72a', 11, 0, 0)

Line : 187
File : sessions.php