"The given key was not present in the dictionary" error on nuget to Standard 2.0 class library.

[rpokrovskij]

Trying to NUGET EntityFramework 6.2 to Standard 2.0 class library project in VS 2017.
Expected: just referenced ef6 (or an understandable error message).

Result: error and output

Restoring packages for D:\cot\DashboardCode\Routines\Routines.Storage.Ef6\Routines.Storage.Ef6.csproj...
System.Collections.Generic.KeyNotFoundException: The given key was not present in the dictionary.
   at System.Collections.Generic.Dictionary`2.get_Item(TKey key)
   at NuGet.Commands.TransitiveNoWarnUtils.ExtractTransitiveNoWarnProperties(RestoreTargetGraph targetGraph, String parentProjectName, HashSet`1 parentProjectWideNoWarn, Dictionary`2 parentPackageSpecificNoWarn, Dictionary`2 warningPropertiesCache)
   at NuGet.Commands.TransitiveNoWarnUtils.CreateTransitiveWarningPropertiesCollection(IEnumerable`1 targetGraphs, PackageSpec parentProjectSpec)
   at NuGet.Commands.RestoreCollectorLogger.get_TransitiveWarningPropertiesCollection()
   at NuGet.Commands.RestoreCollectorLogger.IsWarningSuppressed(IRestoreLogMessage message)
   at NuGet.Commands.RestoreCollectorLogger.Log(IRestoreLogMessage message)
   at NuGet.Commands.RestoreCollectorLogger.Log(ILogMessage message)
   at NuGet.Commands.LockFileBuilder.CreateLockFile(LockFile previousLockFile, PackageSpec project, IEnumerable`1 targetGraphs, IReadOnlyList`1 localRepositories, RemoteWalkContext context)
   at NuGet.Commands.RestoreCommand.BuildAssetsFile(LockFile existingLockFile, PackageSpec project, IEnumerable`1 graphs, IReadOnlyList`1 localRepositories, RemoteWalkContext contextForProject)
   at NuGet.Commands.RestoreCommand.<ExecuteAsync>d__8.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 NuGet.Commands.RestoreRunner.<ExecuteAsync>d__7.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 NuGet.Commands.RestoreRunner.<CompleteTaskAsync>d__10.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 NuGet.Commands.RestoreRunner.<RunWithoutCommit>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 NuGet.PackageManagement.DependencyGraphRestoreUtility.<PreviewRestoreAsync>d__2.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.ValidateEnd(Task task)
   at NuGet.PackageManagement.NuGetPackageManager.<PreviewBuildIntegratedProjectActionsAsync>d__74.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.ValidateEnd(Task task)
   at NuGet.PackageManagement.NuGetPackageManager.<PreviewInstallPackageAsync>d__65.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 NuGet.PackageManagement.UI.UIActionEngine.<GetActionsAsync>d__13.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.ValidateEnd(Task task)
   at NuGet.PackageManagement.UI.UIActionEngine.<>c__DisplayClass7_0.<<PerformActionImplAsync>b__0>d.MoveNext()
Time Elapsed: 00:00:00.0640251
========== Finished ==========

[ajcvickers]

Duplicate of #231 and also see #271