title: Could not load file or assembly 'Microsoft.Extensions.Configuration.Abstractions, Version=5.0.0.0 in Azure Functions
body: <p>I have an API and a separate Azure Functions app. I upgraded my API app to <code>.NET 5</code> and it's working fine. In the API app's solution, I have class library projects that I also reference in my Azure Functions app. These class libraries are <code>netstandard2.1</code> projects.</p>
  <p>Ever since this update -- during which I also updated all my NuGet packages to latest versions -- my Azure Functions app stopped working. I'm getting the following error:</p>
  <blockquote>
  <p>Could not load file or assembly
  'Microsoft.Extensions.Configuration.Abstractions, Version=5.0.0.0,
  Culture=neutral, PublicKeyToken=adb9793829ddae60'. The system cannot
  find the file specified. Value cannot be null. (Parameter 'provider')</p>
  </blockquote>
  <p>I noticed that there were breaking changes involving the <code>Microsoft.Extensions.*</code> packages and their recommendation is to install the package that is causing the issue directly. So I added <code>Microsoft.Extensions.Configuration.Abstractions</code> to my Azure Functions manually -- before it was being installed as a dependency of <code>Microsoft.Extensions.Configuration</code> package. Here's the information about this:
  <a href="https://github.com/dotnet/aspnetcore/issues/21033" rel="noreferrer">https://github.com/dotnet/aspnetcore/issues/21033</a></p>
  <p>The issue still persists. I even tried downgrading <code>Microsoft.Extensions.Configuration</code> in both the API and Functions app, but I'm still getting the same error.</p>
  <p>Any idea how to resolve this issue?</p>