This is how I fixed my issue - Very quickly!
I was trying to install C++ 2019 v14.26xx and getting the .msi error. So going backwards I went to Add/Remove programs and looked for the last version of C++ installed which was C++ 2017 V11.xx (x86 & x64). I removed both which gave the error that they were already uninstalled and asked to remove them from the list. Which I did.
Then went to \HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Installer\Products and found the keys for C++ 2017 I just removed. (there were 4 total 2 x86 & 2 x64). I deleted all 4 keys then ran the C++ 2019 package I originally had the issue with. It installed with no issues.
Hope this helps