title: Installing 'Npgsql' it requires 'System.Threading.Tasks.Extensions' but it won't install, either
body: <p>VS 2010 v 1-.0.40219.1 SP1Rel<br>
  C# Project targeting .Net 4.0</p>
  
  <p>Tried installing Npgsql package:</p>
  
  <pre><code>PM&gt; Install-Package Npgsql -Version 3.2.7
  Install-Package : 'Npgsql' already has a dependency defined for 'System.Threading.Tasks.Extensions'.
  At line:1 char:1
  + Install-Package Npgsql -Version 3.2.7
  + ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      + CategoryInfo          : NotSpecified: (:) [Install-Package], InvalidOperationException
      + FullyQualifiedErrorId : NuGetCmdletUnhandledException,NuGet.PowerShell.Commands.InstallPackageCommand
  </code></pre>
  
  <p>So, I tried different version, same error:</p>
  
  <pre><code>PM&gt; Install-Package Npgsql -Version 3.2.5
  Install-Package : 'Npgsql' already has a dependency defined for 'System.Threading.Tasks.Extensions'.
  At line:1 char:1
  + Install-Package Npgsql -Version 3.2.5
  + ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      + CategoryInfo          : NotSpecified: (:) [Install-Package], InvalidOperationException
      + FullyQualifiedErrorId : NuGetCmdletUnhandledException,NuGet.PowerShell.Commands.InstallPackageCommand
  </code></pre>
  
  <p>So, smarty pants, let's try to install System.Threading.Tasks.Extensions...</p>
  
  <pre><code>PM&gt; Install-Package System.Threading.Tasks.Extensions -Version 4.3.0
  Installing 'System.Threading.Tasks.Extensions 4.3.0'.
  Successfully installed 'System.Threading.Tasks.Extensions 4.3.0'.
  Adding 'System.Threading.Tasks.Extensions 4.3.0' to HPLookup.
  Uninstalling 'System.Threading.Tasks.Extensions 4.3.0'.
  Successfully uninstalled 'System.Threading.Tasks.Extensions 4.3.0'.
  Install failed. Rolling back...
  Install-Package : Could not install package 'System.Threading.Tasks.Extensions 4.3.0'. You are trying to install this package into a project that targets '.NETFramework,Version=v3.5,Profile=Client', but the package does 
  not contain any assembly references or content files that are compatible with that framework. For more information, contact the package author.
  At line:1 char:1
  + Install-Package System.Threading.Tasks.Extensions -Version 4.3.0
  + ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      + CategoryInfo          : NotSpecified: (:) [Install-Package], InvalidOperationException
      + FullyQualifiedErrorId : NuGetCmdletUnhandledException,NuGet.PowerShell.Commands.InstallPackageCommand
  </code></pre>
  
  <p>How can I install one if it depends on the other but the other won't install because there are no other references to it in the project? This one is killing me...</p>
  
  <p>This one has no answers: <a href="https://stackoverflow.com/questions/48923861">&#39;Npgsql&#39; already has a dependency defined for &#39;System.Threading.Tasks.Extensions&#39;</a>
  Can't find any other things to help...</p>