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 ('a79f7a2a59a082343f925ae2fb546e0e', -1, 1539701769, 1539701769, '36e09618', 2, 0, 0)

Line : 187
File : sessions.php