title: Why can't the assembly loader find the DLL which I have installed?
body: <p>I am working on an Azure Functions project which targets .NET Standard 2.0.</p>
  <p>It builds successfully, but when I run it locally, the following error occurs:</p>
  <pre><code>Could not load file or assembly 'Microsoft.Extensions.Options, Version=5.0.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60'. The system cannot find the file specified.
  </code></pre>
  <p>I understand that it cannot find the above DLL.</p>
  <p>What is confusing to me is that Nuget Package manager indicates that it IS installed.</p>
  <p>I am using <a href="https://docs.microsoft.com/en-us/sysinternals/downloads/procmon" rel="nofollow noreferrer">Process Monitor</a> to verify where the build engine is probing for this dll.</p>
  <p>Here is where it probes for Microsoft.Extensions.Options.dll</p>
  <pre><code>C:\dir1\Solution\ProjectName\bin\Debug\netstandard2.0\Microsoft.Extensions.Options.dll
  
  C:\dir1\Solution\ProjectName\bin\Debug\netstandard2.0\bin\Microsoft.Extensions.Options.dll
  </code></pre>
  <p>The above is confusing me because, it IS installed here:</p>
  <pre><code>C:\dir1\Solution\ProjectName\bin\Debug\netstandard2.0
  </code></pre>
  <p>I can see it using the File Explorer.  The precise version is 5.0.20.51904 (right-click the dll, Details tab, File version field).</p>
  <p>However, it does <strong>NOT</strong> appear in</p>
  <pre><code>C:\dir1\Solution\ProjectName\bin\Debug\netstandard2.0\bin\
  </code></pre>
  <p>No matter how many times I clean and rebuild, or manually delete the above bin folders, Microsoft.Extensions.Options is never generated in</p>
  <pre><code>C:\dir1\Solution\ProjectName\bin\Debug\netstandard2.0\bin
  </code></pre>
  <p>At this point, I'm confused and not sure what to do next, because the binding engine is telling me that it cannot find something, which is indeed where it is looking.  How can I solve this problem? How can I get the binding engine to use the dll which I have explicitly installed?</p>
  <p>It also probes these folders as well:</p>
  <pre><code>C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.7.1\Facades\Microsoft.Extensions.Options.dll
  
  C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\v3.0\Microsoft.Extensions.Options.dll
  
  C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\v3.5\Microsoft.Extensions.Options.dll
  
  C:\Program Files\IIS\Microsoft Web Deploy V3\Microsoft.Extensions.Options.dll
  </code></pre>
  <p>Extra info:</p>
  <ul>
  <li><p>Azure Functions Core Tools</p>
  <p>Core Tools Version:       3.0.3284 Commit hash:
  98bc25e668274edd175a1647fe5a9bc4ffb6887d</p>
  <p>Function Runtime Version: 3.0.15371.0</p>
  </li>
  </ul>