Summary: How to fix the installation error: A DLL required for this install to complete could not be run.
Related installation help: Troubleshooting Rhino 5 Installation
Installation fails with a missing dll message like:
There is a problem with the Windows Installer package. A DLL required for this install to complete could not be run. Contact your support personnel or package vendor.
It may be that a virus scanner is getting in the way. Try disabling any virus scanners and retry the installation.
Or your system may be missing important Windows Updates. See how to check for Windows updates here.