Thank you for your feedback! We have fixed this issue and it's available in VS 2107 15.6.3 as of 3/19/2018.

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Just updated to 15.6 final today and nuget is busted. It's just freezing when I go to update packages...

More details in https://developercommunity.visualstudio.com/content/problem/209341/vs-156-pro-all-nuget-calls-now-fail-msbuild-proble.html but that has now been closed as a duplicate in favour of this problem.

I'm not 100% that that is, in fact, the case (my symptoms are a bit different) but I could imagine it's the same issue underlying both.

My symptoms (Xamarin environment)

• Worked fine up through VS 15.5
• With 15.6 selecting "Manage NuGet Packages" I get "Object reference not set to an instance of an object" (even a newly created project)
• Right-clicking the solution and selecting "Restore NuGet Packages" yields "NuGet Package restore failed for project [projectname]: Object reference not set to an instance of an object... Please see Error List window for detailed warnings and errors" (stack trace below)
• Problem persists through an Uninstall Visual Studio / Cleanup / Reinstall
• Projects without NuGet packages can be Built, though a Rebuild will fail
• ApplicationInsights no longer works on any project

Relevant stack trace

Severity Code Description Project File Line Suppression State
Warning The "GetReferenceNearestTargetFrameworkTask" task failed unexpectedly.
System.Runtime.InteropServices.COMException (0x80004005): Error HRESULT E_FAIL has been returned from a call to a COM component.
at EnvDTE.Project.get_UniqueName()
at Microsoft.VisualStudio.ProjectUtilities.GetVsHierarchy(IServiceProvider provider, Project project, Boolean throwOnFailure)
at Microsoft.VisualStudio.Design.VSTypeResolutionService.GetProjectOutputs(Project project)
at Microsoft.VisualStudio.Design.VSTypeResolutionService.AddProjectEntries(Project project, List`1 entries)
at Microsoft.VisualStudio.Design.VSTypeResolutionService.EnsurePopulated(Boolean fPopulateProject)
at Microsoft.VisualStudio.Design.VSTypeResolutionService.SearchProjectEntries(AssemblyName assemblyName, String typeName, Boolean ignoreTypeCase, Assembly& assembly)
at Microsoft.VisualStudio.Design.VSTypeResolutionService.SearchEntries(AssemblyName assemblyName, String typeName, Boolean ignoreCase, Assembly& assembly, ReferenceType refType)
at Microsoft.VisualStudio.Design.VSTypeResolutionService.SearchEntries(AssemblyName assemblyName, String typeName, Boolean ignoreTypeCase, Assembly& assembly)
at Microsoft.VisualStudio.Design.VSTypeResolutionService.System.ComponentModel.Design.ITypeResolutionService.GetType(String typeName, Boolean throwOnError, Boolean ignoreCase)
at Microsoft.VisualStudio.Design.VSTypeResolutionService.System.ComponentModel.Design.ITypeResolutionService.GetType(String name)
at Microsoft.VisualStudio.Design.VSDynamicTypeService.OnTypeResolve(Object sender, ResolveEventArgs e)
at System.AppDomain.OnTypeResolveEvent(RuntimeAssembly assembly, String typeName)
at System.RuntimeTypeHandle.GetTypeByName(String name, Boolean throwOnError, Boolean ignoreCase, Boolean reflectionOnly, StackCrawlMarkHandle stackMark, IntPtr pPrivHostBinder, Boolean loadTypeFromPartialName, ObjectHandleOnStack type)
at System.RuntimeTypeHandle.GetTypeByName(String name, Boolean throwOnError, Boolean ignoreCase, Boolean reflectionOnly, StackCrawlMark& stackMark, IntPtr pPrivHostBinder, Boolean loadTypeFromPartialName)
at System.RuntimeType.GetType(String typeName, Boolean throwOnError, Boolean ignoreCase, Boolean reflectionOnly, StackCrawlMark& stackMark)
at System.Type.GetType(String typeName)
at NuGet.Common.RuntimeEnvironmentHelper.<>c.<.cctor>b_14_0()
at System.Lazy`1.CreateValue()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
at System.Lazy`1.get_Value()
at NuGet.Common.RuntimeEnvironmentHelper.get_IsMono()
at NuGet.Build.MSBuildLogger.Log(ILogMessage message)
at NuGet.Common.LoggerBase.Log(LogLevel level, String data)
at NuGet.Build.Tasks.BuildTasksUtility.LogTaskParam(ILogger log, String direction, String name, String[] values)
at NuGet.Build.Tasks.GetReferenceNearestTargetFrameworkTask.Execute()
at Microsoft.Build.BackEnd.TaskExecutionHost.Microsoft.Build.BackEnd.ITaskExecutionHost.Execute()
at Microsoft.Build.BackEnd.TaskBuilder.<ExecuteInstantiatedTask>d_26.MoveNext() PTR_App_Win_Server 

I'm basically unable to work. The fact that the problem survives an Uninstall / Reinstall cycle leads me to feel that some setting got borked during the update from 15.5 to 15.6, and that once this bug is identified, that it can be tracked back to that setting so I'm not waiting weeks (!!?!) before being able to use VS.

Hi,

I had the same issue with VS 15.6.

Was able to resolve it by removing the protocolVersion from the nuget.config file.

<add key="nuget.org" value="https://api.nuget.org/v3/index.json" protocolVersion="3" />

became:

<add key="nuget.org" value="https://api.nuget.org/v3/index.json" />

After installing 15.6.1 today the error came back and I have no clue haw to resolve it.

Opening the package manager results in a Object Reference not set error

Trying to deploy my Xamarin Forms Droid app results in the following error:

1>Build started.
1>Project "PaperLab.Droid.csproj" (Install target(s)):
1>Project "PaperLab.Apps.Generic.csproj" (GetTargetFrameworks target(s)):
1>Done building project "PaperLab.Apps.Generic.csproj".
1>Project "PaperLab.Apps.Base.csproj" (GetTargetFrameworks target(s)):
1>Done building project "PaperLab.Apps.Base.csproj".
1>The "GetReferenceNearestTargetFrameworkTask" task failed unexpectedly.
1>System.Runtime.InteropServices.COMException (0x80004005): Unspecified error (Exception from HRESULT: 0x80004005 (E_FAIL))
1>   at EnvDTE.Project.get_UniqueName()
1>   at Microsoft.VisualStudio.ProjectUtilities.GetVsHierarchy(IServiceProvider provider, Project project, Boolean throwOnFailure)
1>   at Microsoft.VisualStudio.Design.VSTypeResolutionService.GetProjectOutputs(Project project)
1>   at Microsoft.VisualStudio.Design.VSTypeResolutionService.AddProjectEntries(Project project, List`1 entries)
1>   at Microsoft.VisualStudio.Design.VSTypeResolutionService.EnsurePopulated(Boolean fPopulateProject)
1>   at Microsoft.VisualStudio.Design.VSTypeResolutionService.SearchProjectEntries(AssemblyName assemblyName, String typeName, Boolean ignoreTypeCase, Assembly& assembly)
1>   at Microsoft.VisualStudio.Design.VSTypeResolutionService.SearchEntries(AssemblyName assemblyName, String typeName, Boolean ignoreCase, Assembly& assembly, ReferenceType refType)
1>   at Microsoft.VisualStudio.Design.VSTypeResolutionService.SearchEntries(AssemblyName assemblyName, String typeName, Boolean ignoreTypeCase, Assembly& assembly)
1>   at Microsoft.VisualStudio.Design.VSTypeResolutionService.System.ComponentModel.Design.ITypeResolutionService.GetType(String typeName, Boolean throwOnError, Boolean ignoreCase)
1>   at Microsoft.VisualStudio.Design.VSTypeResolutionService.System.ComponentModel.Design.ITypeResolutionService.GetType(String name)
1>   at Microsoft.VisualStudio.Design.VSDynamicTypeService.OnTypeResolve(Object sender, ResolveEventArgs e)
1>   at System.AppDomain.OnTypeResolveEvent(RuntimeAssembly assembly, String typeName)
1>   at System.RuntimeTypeHandle.GetTypeByName(String name, Boolean throwOnError, Boolean ignoreCase, Boolean reflectionOnly, StackCrawlMarkHandle stackMark, IntPtr pPrivHostBinder, Boolean loadTypeFromPartialName, ObjectHandleOnStack type)
1>   at System.RuntimeTypeHandle.GetTypeByName(String name, Boolean throwOnError, Boolean ignoreCase, Boolean reflectionOnly, StackCrawlMark& stackMark, IntPtr pPrivHostBinder, Boolean loadTypeFromPartialName)
1>   at System.RuntimeType.GetType(String typeName, Boolean throwOnError, Boolean ignoreCase, Boolean reflectionOnly, StackCrawlMark& stackMark)
1>   at System.Type.GetType(String typeName)
1>   at NuGet.Common.RuntimeEnvironmentHelper.<>c.<.cctor>b__14_0()
1>   at System.Lazy`1.CreateValue()
1>--- End of stack trace from previous location where exception was thrown ---
1>   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
1>   at System.Lazy`1.get_Value()
1>   at NuGet.Common.RuntimeEnvironmentHelper.get_IsMono()
1>   at NuGet.Build.MSBuildLogger.Log(ILogMessage message)
1>   at NuGet.Common.LoggerBase.Log(LogLevel level, String data)
1>   at NuGet.Build.Tasks.BuildTasksUtility.LogTaskParam(ILogger log, String direction, String name, String[] values)
1>   at NuGet.Build.Tasks.GetReferenceNearestTargetFrameworkTask.Execute()
1>   at Microsoft.Build.BackEnd.TaskExecutionHost.Microsoft.Build.BackEnd.ITaskExecutionHost.Execute()
1>   at Microsoft.Build.BackEnd.TaskBuilder.<ExecuteInstantiatedTask>d__26.MoveNext()
1>Done building project "PaperLab.Droid.csproj" -- FAILED.
1>Build FAILED.

Edit: Maybe good to mention. My machine has a freshly new installed with win10pro, installed VS2017 (vrs: 15.6) and had these issues. Was able to resolve it as mentioned above. but now with 15.6.1 I am stuck again.

nuget restore in VS 2017 has given me nothing but trouble since upgrading to 15.6. Every so often builds will fail complaining that a reference, which is a nuget reference, is missing. Despite the fact that the build works perfectly fine on command line MSBuild if you do an explicit nuget restore before hand. The only way to fix a broken build in VS seems to be exit VS, build on command line, reload VS and then it builds fine, until the next time it happens to come up again. Extremely frustrating to say the least.

Same problem for me, unable to manage packages from visual studio and to deploy successfully my solution

same problem here

Just solved the problem opening visual studio without opening a solution, deselecting the checkbox that points to my local source:

C:\Program Files (x86)\Microsoft SDKs\NuGetPackages\

under Options -> Nuget packages management -> packages source -> packages source at computer level

(sorry if the translation is not perfect but my VS is not in english language).

After this, I was able to open the nuget manager on my solution

after Update to VS 2017 15.6.1, I have a somewhat similar problem, Nuget window does not crash, but all tabs (Browse, Installed, Updates) stays empty with an ASP.NET Core 2.0 project.
Nuget seems to find updates, but does not display them:

Also encountering this exact problem in VS2017 v15.6.1. Attempting to view associated NuGet Packages for the solution, Visual Studio hangs and eventually crashes. This only appears to be an issue when working within cross-platform solutions, which is preventing Xamarin code from compiling correctly.

Removing the NuGet reference to C:\Program Files (x86)\Microsoft SDKs\NuGetPackages\ does not solve the issue.