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.
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 ;).
Solution
Clean the solution and try again. See Visual Studio Forum for details. It helped in my case.
Try to check your depencency packages and references and try to ensure that all is ok. I fix this problem delete unnecessary and broke dependencies.