We have been developing a simple yet useful Windows 8 App (shall update the link soon), and in the meanwhile to simulate the app we were greeted by the screen shown “Unable to activate Windows Store app. The wwahost.exe process started, but the activation request failed with error ‘E_Fail’. See help for advice on troubleshooting the issue.” We finally found a solution to surpass this issue, and even decided this issue occurs when you are working in Team Foundation or shared coding environment. (Learn how to easily activate developer’s license for Visual Studio 2012 for Windows 8.)
So, how to fix the issue of unable to activate Windows Store app. In fact, the solution is pretty easy (obviously until it was discovered.) On your Solution Explorer menu on the right sidebar, select “Show All Files” then expand bin and bld and delete the Debug Folder in each. You might want to restart Microsoft Visual Studio once to complete fix.
This problem is generally observed when you are programming for Windows or Windows RT in HTML5 environment. I read in StackOverflow for the same problem, that some people saying “deleting build directories doesn’t help” which is not correct, they must clear the working directory’s temporary bin files in order to fix this Unable to activate windows store app issue.
Hope this solves your problem, if not let us know, we could assist you.