Does not contain a static 'main' method suitable for an entry point

Recently I organized my SharePoint solutions, where I had two SharePoint projects with more than 70 supportive class files. I decided to move all supportive files inside a separate project and refer from that project. So I added new empty project on that solution and moved all class files in to that create project. But when I build the solution, I got below error

“Does not contain a static 'main' method suitable for an entry point”

Reason:

I was looking at this issue as well, and in my case the solution was too easy. I added a new empty project to the solution. The newly added project is automatically set as a console application. But since the project added an 'empty' project, no Program.cs existed in that new project. (As expected)

Solution:

All I needed to do was change the output type of the project properties to Class library

 Reference:

http://stackoverflow.com/questions/9607702/does-not-contain-a-static-main-method-suitable-for-an-entry-point