I hit a snag this morning. In was in Visual Studio and notified that the Sitefinity Thunder plugin had an update available. Typically updates are good so I went ahead and updated. Oy, not good. It broke my connection with my existing server. It turns out that you have to update the server version as well, which is something we can't do at this point in time.
To add insult to injury, the only way to get the Thunder Visual Studio Plugin is through the Visual Studio Extensions site and they don't offer a "previous version" download like you can find with NuGet or other package management tools. Fortunately God was looking out for me and I had a separate copy of the .visx file sitting in my downloads folder for some reason. After uninstalling Thunder, existing Visual Studio, and installing this, I was up and running again!!! If you need a copy, you can grab it here.