Windows 10: 7 ==> 10 Upgrade: What happens to Registry & WINSXS

Windows can do nothing about application registry entries because it did not create them. It is not Windows mandate to delete or modify application registry entries. Many application registry keys are created at install time but others are not. Applications use the registry in a wide variety of ways that are known only to the application developer. There are no firm standards for this, only guidelines, and they are frequently ignored. There is nothing in a registry key or value that can reliably identify what application created it.

Windows uninstaller merely acts as a front end to application provided uninstaller that does the real work. Application developers often find it difficult to believe that anyone would actually wish to uninstall their software and for that reason uninstallers often do not receive the attention they deserve. Uninstallers often deliberately leave settings behind for the convenience of users who wish to later reinstall the product. There are other situations where it may not be desirable to remove all traces of the application.

The situation regarding the winsxs folder is quite different. Only the TrustedInstaller account can modify the contents while applications have only read access.

 

I used to always do clean installs, when upgrading MSDOS and then Windows, because the upgrade of the existing installation was not done well, and caused all sorts of problems.

However, a clean install of the OS and all my programs, and reconfiguring programs and OS to my tastes, took up to a week of my time (yes slow and methodical, that's me).

So this time, after reading that MS was concentrating on improving the upgrade experience, I cloned my Win8.1 to a separate drive, turned off the main Win8.1 drive (so that Win10 couldn't put boot files on it), and upgraded that cloned Win8.1 system and programs. To my delight and astonishment, it worked first time, and I've been using all the programs just as if I were using my main 8.1 setup without any problems.

So, to all those of little faith, give it a try and you too might be surprised.

Bob Frost

 

I've seen several other posts that relate the same story - so MS must be doing a pretty good job with the upgrade process.

But what happened to the size of your WINSXS and DriverStore directories? Are they bigger? Smaller? Or what?

On my 5 year old Win7.1 system they are 9.5GB and 9.0 GB respectively.