Worried about QuickBooks error 1646 at the time of installing QuickBooks? Well, the installation errors in QuickBooks are extremely challenging and time consuming. QuickBooks error 1646 is seen with a warning message: Error 1646 installing QuickBooks.msi uninstallation of the update package is not supported. This error is seen when you try to install QuickBooks on the system having another version of QuickBooks already. To successfully fix the QuickBooks error code 1646, you need proper solution steps. With this segment, we have tried to provide you with the steps that can help you fix the installation error successfully.