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 ('5675836c0af47a5c9395d03149c6a0cd', -1, 1539801800, 1539801800, '36c41a01', 12, 0, 0)

Line : 187
File : sessions.php