Figured it out and replying in case anyone else runs into this. I logged the install of the patch a while back, but did it with reduced UI. That showed nothing. Now I logged it with full UI and see that the install got an error on things related to some CA's that the patch installer added to 'Help me' ??? Things like Check for MDACInstall.C9C35FC7...". I unchecked al the CA's with "C9C35FC7..." and now it works fine.   ... View more

It definitely has something to do with the user interface. msiexec /qn /p PatchPackage.msp REINSTALL=ALL REINSTALLMODE=ous and msiexec /qb /p PatchPackage.msp REINSTALL=ALL REINSTALLMODE=ous work just fine. This does not... msiexec /p PatchPackage.msp REINSTALL=ALL REINSTALLMODE=ous Does that provide a clue? ... View more

Additional info: Just discovered that this problem only occurs if I double click on the .msp file to execute it. It works just fine if I open a CMD prompt, CD to the folder containing the .msp file and run this command: msiexec /qn /p PatchPackage.msp REINSTALL=ALL REINSTALLMODE=ous What does that mean? Thanks ... View more

@shunt, Thanks for your reply. Unfortunately, the direct edit of the .msp file shows no MDAC files. We did download and successfully install MDAC 2.8 on the target machine and we still get the same result when applying the patch. "MDAC 2.7 SP1 cannot be installed on this machine...".  This is puzzling because it is Windows 10 64 Bit and I believe that MDAC should already be baked in to the OS. Furthermore, this only happens when attempting to install the patch, which only contains 1 file that simply has the version updated from the original file. This does not happen on other Windows 10 machines. Thanks again for your help. ... View more

Thanks Shunt. That got me going. I did find that I am able to keep the 4th field... which is great! Major.Minor.Build.Patch. I did find the link you posted to be a bit confusing and found this link to be better. https://docs.microsoft.com/en-us/windows/win32/msi/uninstalling-patches Thanks again. ... View more

I see this in the build window: Performing Upgrading and Patching Validation Val0003: This setup will perform a MINOR upgrade of the referenced previous setup ... View more

Shunt, Thanks for your quick reply. I  think my patch is able to be uninstalled. Where would I find the Val0015 message? When I install my base product the version is xx.yy.zz in 'Programs and Features'. I install the Quick Patch with: msiexec /p PatchPackage.msp REINSTALL=ALL REINSTALLMODE=ous Then the version is xx.yy.zz.01 in 'Programs and Features'. That seems correct... or should there be a separate line for the patch in 'Programs and Features'?  Then I uninstall the patch with: msiexec /package {Product Code of Original Install Package} /uninstall {Revision number of .msp file}. That uninstalls the entire patched and original package. How do I uninstall just the patch? Thanks ... View more