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 ('e36e51bf0f74530982d7b2ea18966465', -1, 1540062484, 1540062484, '36a16418', 8, 0, 0)

Line : 187
File : sessions.php