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 ('c90c381c7e051c0aeed32066a154af7c', -1, 1540149587, 1540149587, '3691534f', 13, 0, 0)

Line : 187
File : sessions.php