Can you try the following to see if this makes any difference?
1. Try the issue with a dummy test project with a single test (in a new, blank solution). Do you see the same behaviour?
2. Assuming you do see the crash happen for the above, try changing the project's build platform to x64, then x86. Try the debugger with each of these platforms. Do you see consistent results?
3. Inside your test code, try adding a Thread.Sleep(20000) to cause the test to wait for 20 seconds during its execution and set a breakpoint on a line of code after this. Run the test using NCrunch without the debugger. Using VS, try attaching the debugger onto the test process running the test (if you're not sure which NCrunch.TestHost is running the test, just attach to all of them). Does the debugger hit the breakpoint? Do you see a crash?
I'll be honest here - it's likely to be very hard for me to troubleshoot this problem for you. I haven't been able to reproduce this issue in any test environment that I have access to. With the issue being kicked up far downstream inside the debugger itself, we don't really have much information to work with. I feel like the best we can hope for here is to narrow down the circumstances under which the debugger will fail to launch in order to help you find a workaround. If you haven't already, I strongly recommend uninstalling and reinstalling VS2015 to see if this makes any difference. Also try disabling any virus scanners or security related software to see if this helps. I suspect that something in your environment is either corrupt or inhibited somehow.
