Visual Studio 2017: A fatal error has occurred and debugging needs to be terminated

Question

When executing unit tests in debugging mode, I get the following error message:

A fatal error has occurred and debugging needs to be terminated. For more 
details please see the Microsoft Help and Support web site. 
HRESULT=0x8000ffff. ErrorCode=0x0.

Answer 1

So my steps to fix the issue,

1- [Preventive action] Update the Visual studio 2017 , from the yellow flag notification or from

Tools >> Extensions & Updates >> Updates >> visual studio marketplace.

2- Search in your test solution for launchsettings.json file and remove it.

3- Clean the test solution .

4- Rebuild the project .

5- Make a cup of coffee ;).

Answer 2

Restarting Visual Studio solved this issue for me.

Answer 3

Cleaning the solution didn't work for me, and I couldn't find a launchsettings.json.

What eliminated the error for me: Changing the Startup project to a project other than the test project, as mentioned in this MSDN forum post.