ClickOnce publishing XBAP applications and F5 debugging not working
Some times, when you publish an XBAP application using ClickOnce, you cannot debug the same application afterwards using F5. This is due to a change to the project settings (debug tab). The extension is removed from the command-line argument to PresentationHost.exe (-debug
.xbap). Insert the .xbap extension and things work alright again.