Could not find 'WindowsFormsApplication1.Program' specified for Main method after renaming name space

Question

I have a C# app that had the default namespace WindowsFormsApplication1.

I decided that I would like to use a different namespace so I renamed WindowsFormsApplication1. Now when I compile I get the error:

Could not find 'WindowsFormsApplication1.Program' specified for Main method.

To rename the namespace I highlighted the namespace in a file and hit F2.

How do I resolve this and change the actual namespace through out the project?

I am using Visual C# 2010 Express.

Answer 1

In project -> properties change "startup object" to the new namespace.

Answer 2

You should rename through the "Refаctor" feature of Visual Studio.

Answer 3

As Mausimo says you need to select the 'Startup object' in Project -> References, however I was finding that the new namespace was not being shown here; I could only select the old namespace or '(Not set)'. If you find the same then it appears VS (this is on 2013) does not pick up the change immediately, restart VS and you can then select the class under the new namespace.