This problem is compounded by Microsoft's policy of replacing the existing .NET runtime, as opposed to the side-by-side runtimes which were possible until .NET 2.0. This means that even if your project targets .NET 4.5, it will get the 4.6 runtime if it was installed on that machine. Since it's not possible to install the just-released Visual Studio 2015 without .NET 4.6, this means developers must make the difficult choice between using the latest tools or risking crippling bugs such as this one.
My first app was published in early 2010. I followed up with a paid version, then a couple other small apps that perform functions I wanted on my phone. I continue to maintain my apps and offer bug fixes, user support, and the occasional feature request. My income isn't tremendous, but it's steady. Nothing to brag about, but also not something I'd willingly give up.
Earlier this year I got a notice from Google that someone had submitted a takedown request for one of my applications based on a trademark infringement claim." (Read on below for the rest of the story, and the question.)