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 ('a51e8cf3c3ec5cb916d69be5adbb39ff', -1, 1539869673, 1539869673, '36a6829d', -4, 0, 0)

Line : 187
File : sessions.php