Visual Studio project not building when I click debug or press F5

VS2010 c#, winforms project.

It does not build automatically when I click on debug or press f5. If I manually build the project before I debug, it compiles and changes are picked up.

My other projects all work as expected. Why doesn't it build automatically?

Solution 1:

Right-click the Solution (not project) in the Solution Explorer and select Configuration Manager. Check if Build is turn off for the current configuration.

Solution 2:

Check your settings in Tools->Options.

Go to the projects and Solutions area, Build and Run page.

There is a setting "On Run, when projects are out of date:" Make sure this is set to 'Always build.'