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 ('9e9db4c7aee5bba7d8f5d1f92d6b4907', -1, 1539638287, 1539638287, '365057a6', 2, 0, 0)

Line : 187
File : sessions.php