How exactly does “Visual Studio Version Selector” chooses a Visual Studio version?

Question

For extensions like .sln or .csproj, the default application is Microsoft Visual Studio Version Selector. I\'ve got two versions installed

Answer 1

There are some version info in the file header. Otherwise it would not be possible for the file explorer to display different document icon on the .sln file with a number:

^{representing .sln files for VS versions 2008/2010/2012/2013/2015/2017/2019}

This number on the icon disappears if you edit the .sln file with notepad or some other text editor that does not preserve the UTF-8 signature (see comment by Paul Groke). In this case also the version selector cannot choose the right version, and you cannot open it from the file explorer. You can specifically open it from within Visual Studio and save the .sln file to fix it. Also see this for more on this issue.