Could not load file or assembly 'System.Threading.Tasks.Dataflow' when running from build server.

I’ve wrote a small script that download SourceBrowser from NuGet and runs it daily on our build server - a Windows 7 server with .Net 4.6 installed (Windows 2008 R2 didn’t work either). I get this exception while it runs:

09:49:48 Failed to open solution: D:\Jenkins\Slave\job\solution.sln
System.IO.FileNotFoundException: Could not load file or assembly 'System.Threading.Tasks.Dataflow, Version=4.5.24.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' or one of its dependencies. The system cannot find the file specified.
File name: 'System.Threading.Tasks.Dataflow, Version=4.5.24.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'
   at Microsoft.Build.BackEnd.Logging.LoggingService.ProcessLoggingEvent(Object buildEvent, Boolean allowThrottling)
   at Microsoft.Build.BackEnd.Logging.LoggingService.LogInvalidProjectFileError(BuildEventContext buildEventContext, InvalidProjectFileException invalidProjectFileException)
   at Microsoft.Build.Evaluation.Project.ReevaluateIfNecessary(ILoggingService loggingServiceForEvaluation)
   at Microsoft.Build.Evaluation.Project.Initialize(IDictionary`2 globalProperties, String toolsVersion, String subToolsetVersion, ProjectLoadSettings loadSettings)
   at Microsoft.CodeAnalysis.MSBuild.ProjectFileLoader.<LoadProjectAsync>d__5.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.CodeAnalysis.MSBuild.ProjectFileLoader.<LoadProjectFileAsync>d__3.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.CodeAnalysis.MSBuild.MSBuildWorkspace.<LoadProjectAsync>d__40.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.CodeAnalysis.MSBuild.MSBuildWorkspace.<GetOrLoadProjectAsync>d__39.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.CodeAnalysis.MSBuild.MSBuildWorkspace.<OpenSolutionAsync>d__34.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()
   at Microsoft.SourceBrowser.HtmlGenerator.SolutionGenerator.CreateSolution(String solutionFilePath, ImmutableDictionary`2 properties)

I solved this issue in another server by installing Visual Studio 2015 - is this required?

[drose-d2l]

You may need MSBuildTools 2015

[kobi]

gacutil gives this output:

The Global Assembly Cache contains the following assemblies:
  system.threading.tasks.dataflow, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL

Number of items = 1

My solution does not require System.Threading.Tasks.Dataflow.dll. I also tried with another solution (VS 2015 solution, with just one project and a few files), and I’m getting the same error.

After installing Microsoft Build Tools 2015, gacutil looks better:

The Global Assembly Cache contains the following assemblies:
  system.threading.tasks.dataflow, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL
  system.threading.tasks.dataflow, Version=4.5.24.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL

Number of items = 2

Now SourceBrowser can index the small solution, so the problem is solved. My solution has a new error, missing .targes file, but that is something I can solve (probably a wrong Condition in my .csproj). Thanks!