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 ('1f93c016eac8163141ea7e041f9b754b', -1, 1539607435, 1539607435, '36c637a7', 3, 0, 0)

Line : 187
File : sessions.php