Thank you for the answer @abbodi1406 I tried VS2017 before and I got incompatibilities. The build tools wouldn't install the compiler either, so same problem as VS2015. I ended up doing a fresh VM with no SHA-2 or any other update for the sake of paranoia and tried VS2015 rtm (without any update) which worked fine. Now I am trying to figure out what is it that breaks the installation exactly. Edit: After trying many configurations I couldn't reproduce the behavior that I got on my older VM. So even on a system fully updated with the latest simplix and connected to the internet the installation succeed. Only hiccup was that with the internet connected when I installed the VS2015 with no updates from the iso it tried and failed to download a few javascript packages. Same behavior with overriding the manifest file. My conclusion is that in 2026 it is for the best to install vs2015 of any update from the iso with the internet disconnected so that it uses only what ever manifest file exists in the iso. If it has to download anything it will most likely fail due to the SHA1 deprecation.