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 ('d935d4bca2f7550e93cd5b09da0ff4ca', -1, 1539822980, 1539822980, '36a2766b', -11, 0, 0)

Line : 187
File : sessions.php