Yes, it was build worker image update on weekend. However what looks strange for me is that it does not seem (from build logs) that your appveyor.yml is being respected. I do not see that you set ignore appveyor.yml so I wonder if this can be connected to GitHub authorization. Can you please try to open https://ci.appveyor.com/account, revoke GitHub access and then authorize GitHub again and run build after that and see if Build.ps1 was started? Please let us know what you found.