A setup project I was working on in Microsoft Visual Studio suddenly stopped building with the following error;
An error occurred while validating. HRESULT = '8001010E'
When I tried to refresh the dependencies I got a nasty error message. If found this post and played with the suggested settings a bit without any joy. Then I shut-down visual studio and restarted and the build error went away! So if this happens to you all I can suggest is to take a look at this post or restart Visual Studio, or both!