The Visual Studio version selector, is a really useful tool, but way too often it comes up with “Version: unrecognized version”, and won’t allow you to open your files. So how do you get from here to there?
This has been reported to Microsoft who have responded that this is “by design”. Wow – must have been a shitty design then!
The upshot is that the version selector is really picky about what it allows in terms of white-space. Unix-encoding for your line-terminators? BZZZZZT! A blank line to start the file? BZZZZZT!
Make sure you are using Windows encoding for your file (Notepad++ is very useful for this: Edit → EOL Conversion → Windows Encoding), and that there are no blank lines at the start of the file. There are a few other ways you could break it with white-space, but they’re the two my source-control seems to like to do.