QuickBooks Error 1321 Whenever you install or update the application, the Windows installer needs to edit many QBDT program files. However, if the Windows installer lacks the required credentials, you experience a number of installation and update issues. In this case, QuickBooks error 1321 appears immediately when you start the QBDT update or installation. Along with this issue, you see a notification on your screen stating, “ The installer has insufficient privileges to mod