This morning, while I added my existing SharePoint project to a solution it start giving me this Error when I do the build.
Error 8 Value cannot be null.Parameter name: PublicKey
Graphically
Strange, because the last time when I run this project it was working fine. Search on the internet doesn’t prove to be much fruitful. So, I compare this project with the existing project which are working fine and realize that for some reason Visual Studio remove the Sign the Assembly checkbox on the project properties and the Public Key is not available. Like below.
So just check the “Sign the assembly” check box which means that you are signing your assembly with the public key which will now available to Visual Studio to build your SharePoint Project and the error will disappear.