We have a couple of web applications that we develop that become completely bricked if one updates his/her development machine to Windows 10 Anniversary Update (1607).
I have stepped through one of the applications in the debugger in Visual Studio 2015; it looks like the site makes it all the way through the Application_Start method, and then immediately crashes after that method returns. We have another web application that does not exhibit these symptoms, but we have not yet nailed down what is different about the app that still works.
I have captured and analyzed one of these crashes using DebugDiag -- I will attach a crash report to this report.
You can see more details here: https://forums.asp.net/t/2104259.aspx?FatalExecutionEngineError+after+Windows+10+Anniversary+Update.
I am probably missing some key info, so please ask if you need more. Thanks!