.Net 2.0 to .Net 4.7.1 migrations

I am migrating our project from .Net 2 to .Net 4.7.1 but I am facing the general problem that is:

Could not load file or assembly 'Managers, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null' or one of its dependencies. A strongly-named assembly is required. (Exception from HRESULT: 0x80131044)

I have tried to make assembly strongName and then reference it to the project but it unfortunately could not solve my problem. Could you please give me a properly solution about this problem.

thank you so much for your help. I solve the problem. We are working on a big project and this project depends many project. So one of these project had been signed. The problem occur this project. I unsigned this projects assembly and then problem solved.