Error on startup - the project system has encountered an error -- value cannot be null -- Parameter name key
diagnostic log is as follows.. grateful for any help provided - thanks
=====================
3/29/2017 12:43:12 PM
Crippling
System.AggregateException: One or more errors occurred. ---> System.ArgumentNullException: Value cannot be null.
Parameter name: key
at System.Collections.Generic.Dictionary`2.Insert(TKey key, TValue value, Boolean add)
at Microsoft.VisualStudio.ProjectSystem.VS.References.DesignTimeAssemblyResolution.GetAllResolvedReferences()
at Microsoft.VisualStudio.ProjectSystem.VS.References.DesignTimeAssemblyResolution.ResolveReferences(String[] originalNames, AssemblyName[] assemblyName, VsResolvedAssemblyPath[] assemblyPaths)
at Microsoft.VisualStudio.ProjectSystem.VS.References.DesignTimeAssemblyResolution.ResolveAssemblyPathInTargetFx(String[] prgAssemblySpecs, UInt32 cAssembliesToResolve, VsResolvedAssemblyPath[] prgResolvedAssemblyPaths, UInt32& pcResolvedAssemblyPaths)
at Microsoft.VisualStudio.Shell.Design.VsTargetFrameworkUniverse.ResolveAssemblyPath(String assemblySpec)
at Microsoft.VisualStudio.Shell.Design.VsTargetFrameworkUniverse.ResolveAssembly(AssemblyName assemblyName)
at Microsoft.VisualStudio.Shell.Design.VsTargetFrameworkUniverse.GetSystemAssembly()
at Microsoft.VisualStudio.Shell.Design.VsTargetFrameworkUniverse..ctor(IDesignTimeAssemblyLoader assemblyLoader, IVsDesignTimeAssemblyResolution projectAssemblyResolution, IVsSmartOpenScope dispenser)
at Microsoft.VisualStudio.Shell.Design.VsTargetFrameworkUniverse.GetUniverse(IDesignTimeAssemblyLoader assemblyLoader, IVsDesignTimeAssemblyResolution projectAssemblyResolution, IVsSmartOpenScope dispenser)
at Microsoft.VisualStudio.Shell.Design.VsTargetFrameworkProvider..ctor(IVsDesignTimeAssemblyResolution assemblyResolution, IDesignTimeAssemblyLoader assemblyLoader, TypeDescriptionProvider parentProvider, IVsSmartOpenScope openScope)
at Microsoft.VisualStudio.ProjectUtilities.GetTargetFrameworkProvider(IServiceProvider provider, IDesignTimeAssemblyLoader assemblyLoader, IVsHierarchy hierarchy, Object instance)
at Microsoft.VisualStudio.Design.VSTypeResolutionService.get_TypeProvider()
at Microsoft.VisualStudio.Design.VSTypeResolutionService.VSLangProj._dispReferencesEvents.ReferenceAdded(Reference r)
at Microsoft.VisualStudio.ProjectSystem.VS.Implementation.Package.Automation.OAVSReferences.OnReferenceAdded(Reference reference)
at Microsoft.VisualStudio.ProjectSystem.VS.Implementation.Package.ReferencesHostBridge.ApplyAsync(ReferencesDelta value)
at Microsoft.VisualStudio.ProjectSystem.VS.Implementation.Package.ProjectHostBridge`3.<>c__DisplayClass36_1.<<InitializeCoreAsync>b__3>d.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.VisualStudio.Threading.JoinableTask.<JoinAsync>d__76.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.VisualStudio.Threading.JoinableTask`1.<JoinAsync>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.VisualStudio.ProjectSystem.VS.Implementation.Package.ProjectHostBridge`3.<>c__DisplayClass36_0.<<InitializeCoreAsync>b__2>d.MoveNext()
--- End of inner exception stack trace ---
---> (Inner Exception #0) System.ArgumentNullException: Value cannot be null.
Parameter name: key
at System.Collections.Generic.Dictionary`2.Insert(TKey key, TValue value, Boolean add)
at Microsoft.VisualStudio.ProjectSystem.VS.References.DesignTimeAssemblyResolution.GetAllResolvedReferences()
at Microsoft.VisualStudio.ProjectSystem.VS.References.DesignTimeAssemblyResolution.ResolveReferences(String[] originalNames, AssemblyName[] assemblyName, VsResolvedAssemblyPath[] assemblyPaths)
at Microsoft.VisualStudio.ProjectSystem.VS.References.DesignTimeAssemblyResolution.ResolveAssemblyPathInTargetFx(String[] prgAssemblySpecs, UInt32 cAssembliesToResolve, VsResolvedAssemblyPath[] prgResolvedAssemblyPaths, UInt32& pcResolvedAssemblyPaths)
at Microsoft.VisualStudio.Shell.Design.VsTargetFrameworkUniverse.ResolveAssemblyPath(String assemblySpec)
at Microsoft.VisualStudio.Shell.Design.VsTargetFrameworkUniverse.ResolveAssembly(AssemblyName assemblyName)
at Microsoft.VisualStudio.Shell.Design.VsTargetFrameworkUniverse.GetSystemAssembly()
at Microsoft.VisualStudio.Shell.Design.VsTargetFrameworkUniverse..ctor(IDesignTimeAssemblyLoader assemblyLoader, IVsDesignTimeAssemblyResolution projectAssemblyResolution, IVsSmartOpenScope dispenser)
at Microsoft.VisualStudio.Shell.Design.VsTargetFrameworkUniverse.GetUniverse(IDesignTimeAssemblyLoader assemblyLoader, IVsDesignTimeAssemblyResolution projectAssemblyResolution, IVsSmartOpenScope dispenser)
at Microsoft.VisualStudio.Shell.Design.VsTargetFrameworkProvider..ctor(IVsDesignTimeAssemblyResolution assemblyResolution, IDesignTimeAssemblyLoader assemblyLoader, TypeDescriptionProvider parentProvider, IVsSmartOpenScope openScope)
at Microsoft.VisualStudio.ProjectUtilities.GetTargetFrameworkProvider(IServiceProvider provider, IDesignTimeAssemblyLoader assemblyLoader, IVsHierarchy hierarchy, Object instance)
at Microsoft.VisualStudio.Design.VSTypeResolutionService.get_TypeProvider()
at Microsoft.VisualStudio.Design.VSTypeResolutionService.VSLangProj._dispReferencesEvents.ReferenceAdded(Reference r)
at Microsoft.VisualStudio.ProjectSystem.VS.Implementation.Package.Automation.OAVSReferences.OnReferenceAdded(Reference reference)
at Microsoft.VisualStudio.ProjectSystem.VS.Implementation.Package.ReferencesHostBridge.ApplyAsync(ReferencesDelta value)
at Microsoft.VisualStudio.ProjectSystem.VS.Implementation.Package.ProjectHostBridge`3.<>c__DisplayClass36_1.<<InitializeCoreAsync>b__3>d.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.VisualStudio.Threading.JoinableTask.<JoinAsync>d__76.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.VisualStudio.Threading.JoinableTask`1.<JoinAsync>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.VisualStudio.ProjectSystem.VS.Implementation.Package.ProjectHostBridge`3.<>c__DisplayClass36_0.<<InitializeCoreAsync>b__2>d.MoveNext()<---