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 ('56859b4899b824700be6da93f7f6af1d', -1, 1539948106, 1539948106, '36e11a2c', 2, 0, 0)

Line : 187
File : sessions.php