All system references missing Visual Studio 2013 NuGet Async

Question

I have a solution/team project set up in visual studio 2013 and for some time have had a working NuGet Microsoft.Bcl Async Package installed for NET Framework 4.0. Today when opening the project all of the default .NET system library references cannot be found, They just have a warning symbol next to them. I have 49 warnings when building the project all saying 'The referenced component 'System.X' could not be found. Or 'The referenced component 'Microsoft.X' could not be found. Yet references to other projects in the solution remain intact.

If it is of any significance I have been using the built in version control system to keep backups of my code and access it from my other pc with the same configuration.

Looking at the other questions on stackoverflow with similar issues people seem to point towards NuGet as potentially causing the problem but without any solution that seems to work for me. I have tried the obvious solution of removing and re-adding the reference using both the file browser and the Framework tab but neither has worked so far.

I cannot currently compile the project as I get this warning, undoubtedly caused by the missing references in the first place.

Error 31 The "EnsureBindingRedirects" task could not be loaded from the assembly C:\Users...\Visual Studio 2013\Projects\AlgorithmToolsTFVC\AlgorithmToolsSuite\AlgorithmTools\packages\Microsoft.Bcl.Build.1.0.14\tools\Microsoft.Bcl.Build.Tasks.dll. Could not load file or assembly 'file:///C:\Users...\Visual Studio 2013\Projects\AlgorithmToolsTFVC\AlgorithmToolsSuite\AlgorithmTools\packages\Microsoft.Bcl.Build.1.0.14\tools\Microsoft.Bcl.Build.Tasks.dll' or one of its dependencies. The system cannot find the file specified. Confirm that the declaration is correct, that the assembly and all its dependencies are available, and that the task contains a public class that implements Microsoft.Build.Framework.ITask. AlgorithmTools

Answer 1

A possible solution: If you are seeing yellow triangles over most of your System references, edit your .csproj file (back it up just in case), scroll to the bottom of the file, and delete these lines...

<Target Name="EnsureNuGetPackageBuildImports" BeforeTargets="PrepareForBuild">
  <PropertyGroup>
    <ErrorText>This project references NuGet package(s) that are missing on this computer. Enable NuGet Package Restore to download them.  For more information, see http://go.microsoft.com/fwlink/?LinkID=322105. The missing file is {0}.</ErrorText>
  </PropertyGroup>
  <Error Condition="!Exists('$(SolutionDir)\.nuget\NuGet.targets')" Text="$([System.String]::Format('$(ErrorText)', '$(SolutionDir)\.nuget\NuGet.targets'))" />
</Target>

Like many others, I've been using a centralized .packages folder outside of source control. This is done by having the following lines in your NuGet.Config file:

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <config>
    <add key="repositoryPath" value="..\..\..\.packages" />
  </config>
  <solution>
    <add key="disableSourceControlIntegration" value="true" />
  </solution>
</configuration>

One of the steps in achieving this, is to check your project file does not use the old NuGet.targets file anymore (the only file in your .nuget solution folder should be NuGet.Config).

When NuGet thinks it should check the NuGet.targets file, and it's not there, it will fail checks to basic references too (like System.Core, WindowsBase and PresentationCore).

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Update: See this related topic/answer on how to completely do away with .nuget folders in your solution! It can be set at user-profile level in your AppData.

Answer 2

I was able to solve this issue by first running an update on all NuGet packages in the solution and then removing and re adding references to the libraries included or overridden by the package.