I get a filenotfoundexception for a nuget package

I get a filenotfoundexception which sites MIcrosoft.Extensions.DependencyInjection v3.1.3. I have this precise nuget package installed and have uninstalled and reinstalled it. Why would I be getting this error when the nuget package is installed? I am trying to run a dot net core 3.1 api on my local machine using IIS Express