Visual Studio 2010 debug not starting, F5 or click on “Play” not working, not doing anything. Waiting 2-3 minutes solves the issue

Question

I have a relatively simple C# (Framework 4) console application. When I click the \"Play\" icon or hit F5 (i.e. start the program in debug mode), the icon becomes gra

Answer 1

Apparently there are many root causes for this. In my case - opened an old application for the first time in VS2010. The solution was upgraded. Everything compiles without error - but app won't start. There are half a dozen class libraries linked to the application. Turns out one of them was still compiling to .Net Framework 3.5, whereas all the others had automatically upgraded to .Net Framework 4. Likely there was an error message in the conversion log, whose import I didn't heed at the time. Once I changed that last library to use 4 instead of 3.5, everything ran smoothly.