UNABLE TO INSTALL UPDATE - UPDATE STOPS AT 30% -WRITING SYSTEM REGISTRY VALUES - THEN RECEIVE ERROR 1712

I appreciate you letting us know, Nancy78191. I've got fixes to help troubleshoot errors when installing updates in your company file. 

QuickBooks Desktop uses Microsoft programs to run web-based aps. This error occurs when one or more Windows components are missing. To rectify this error, let's download the QuickBooks Tools Hub into your account. Beforehand, it's best to secure a backup copy of your company file and ensure your QuickBooks Desktop is on its latest release. This way, you'll always have its recent features and fixes. To begin: 

1. Close QuickBooks.
2. Download the most recent version (1.6.0.3) of the QuickBooks Tool Hub. Save the file somewhere you can easily find it (like your Downloads folder or your Windows desktop). Note: If you've installed Tool Hub before, you can find out which version you have. Select the Home tab.  The version will be on the bottom.
3. Open the file you downloaded (QuickBooksToolHub.exe).
4. Follow the on-screen steps to install and agree to the terms and conditions.
5. When the installation finishes, double-click the icon on your Windows desktop to open the tool hub.

Then, run the Quick Fix my Program from the tool hub. You can refer to this guide for more detailed information: Error 1712 when installing QuickBooks for Desktop. 

However, if the issue persists, add or create a Windows user with Administrator rights, then attempt QuickBooks installation.

Moreover, I'm sharing this reference to further guide you with other fixes of your data file: Fix issues when QuickBooks has stopped working. 

I'll always be available in this forum if there's anything else you require assistance installing updates in your account. Feel free to leave your queries in the comments below. Keep safe.