Could not load file or assembly 'System.ComponentModel.Annotations

Question

I have a Framework 4.7.2 Unit Test calling a .NetStandard2.0 project

The debugger indicates the test is failing in some data access code.

The error is

Test method UnitTestProject3.UnitTest1.TestMethod1 threw exception: 
System.IO.FileNotFoundException: Could not load file or assembly 'System.ComponentModel.Annotations, Version=4.2.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' or one of its dependencies. The system cannot find the file specified.
    at Microsoft.EntityFrameworkCore.Metadata.Conventions.Internal.CoreConventionSetBuilder.CreateConventionSet()
   at Microsoft.EntityFrameworkCore.Infrastructure.ModelSource.CreateConventionSet(IConventionSetBuilder conventionSetBuilder)
   at Microsoft.EntityFrameworkCore.Infrastructure.ModelSource.CreateModel(DbContext context, IConventionSetBuilder conventionSetBuilder, IModelValidator validator)
   at Microsoft.EntityFrameworkCore.Infrastructure.ModelSource.<>c__DisplayClass5_0.<GetModel>b__1()
   at System.Lazy`1.CreateValue()
   at System.Lazy`1.LazyInitValue()
   at System.Lazy`1.get_Value()
   at Microsoft.EntityFrameworkCore.Infrastructure.ModelSource.GetModel(DbContext context, IConventionSetBuilder conventionSetBuilder, IModelValidator validator)
   at Microsoft.EntityFrameworkCore.Internal.DbContextServices.CreateModel()
   at Microsoft.EntityFrameworkCore.Internal.DbContextServices.get_Model()
   at Microsoft.EntityFrameworkCore.Infrastructure.EntityFrameworkServicesBuilder.<>c.<TryAddCoreServices>b__7_2(IServiceProvider p)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitFactory(FactoryCallSite factoryCallSite, ServiceProviderEngineScope scope)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSite(IServiceCallSite callSite, TArgument argument)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitScoped(ScopedCallSite scopedCallSite, ServiceProviderEngineScope scope)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSite(IServiceCallSite callSite, TArgument argument)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitConstructor(ConstructorCallSite constructorCallSite, ServiceProviderEngineScope scope)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSite(IServiceCallSite callSite, TArgument argument)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitScoped(ScopedCallSite scopedCallSite, ServiceProviderEngineScope scope)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSite(IServiceCallSite callSite, TArgument argument)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.DynamicServiceProviderEngine.<>c__DisplayClass1_0.<RealizeService>b__0(ServiceProviderEngineScope scope)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceProviderEngine.GetService(Type serviceType, ServiceProviderEngineScope serviceProviderEngineScope)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceProviderEngineScope.GetService(Type serviceType)
   at Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetRequiredService(IServiceProvider provider, Type serviceType)
   at Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetRequiredService[T](IServiceProvider provider)
   at Microsoft.EntityFrameworkCore.DbContext.get_DbContextDependencies()
   at Microsoft.EntityFrameworkCore.DbContext.get_InternalServiceProvider()
   at Microsoft.EntityFrameworkCore.DbContext.get_DbContextDependencies()
   at Microsoft.EntityFrameworkCore.DbContext.get_Model()
   at Microsoft.EntityFrameworkCore.Internal.InternalDbSet`1.get_EntityType()
   at Microsoft.EntityFrameworkCore.Internal.InternalDbSet`1.get_EntityQueryable()
   at Microsoft.EntityFrameworkCore.Internal.InternalDbSet`1.System.Linq.IQueryable.get_Provider()
   at System.Linq.Queryable.SingleOrDefault[TSource](IQueryable`1 source, Expression`1 predicate)
   at SBD.VivPackAndSend.PackAndSend.GetReadyBy(Int32 headId, String connectionString) in D:\devnet10\SBD.Common\SBD.VivPackAndSend\PackAndSend.cs:line 65
   at UnitTestProject3.UnitTest1.TestMethod1() in D:\devnet10\SBD.Common\UnitTestProject3\UnitTest1.cs:line 15

The .NetStandard2.0 project file is

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <OutputType>Library</OutputType>
    <TargetFramework>netstandard2.0</TargetFramework>
    <CopyLocalLockFileAssemblies>true</CopyLocalLockFileAssemblies>
  <ApplicationIcon />
    <StartupObject />
    <SignAssembly>true</SignAssembly>
    <AssemblyOriginatorKeyFile>Software by Design.snk</AssemblyOriginatorKeyFile>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Microsoft.EntityFrameworkCore" Version="2.2.6" />
    <PackageReference Include="Microsoft.EntityFrameworkCore.Relational" Version="2.2.6" />
    <PackageReference Include="Microsoft.EntityFrameworkCore.SqlServer" Version="2.2.6" />
    <PackageReference Include="Microsoft.Extensions.Configuration.Json" Version="2.2.0" />
  </ItemGroup>

  <ItemGroup>
    <ProjectReference Include="..\StandardCommon\SBD.StandardCommon.csproj" />
  </ItemGroup>

</Project>

I looked at this similar question and tried to add a reference to System.ComponentModel.Annotations using VS2019->Tools->Manage Nuget Packages for solution

But the lowest version available is 4.4.0

I tried it anyway but it did not help.

https://learn.microsoft.com/en-us/dotnet/framework/configure-apps/redirect-assembly-versions — Lee Taylor, Aug 24 '19 at 21:29

score 0 · Answer 1 · answered Aug 24 '19 at 22:24

0

I tried the unit test in a .netcore2.1 test project. I got a different error there, which caused me to realise there was a problem in my connection string.

When I fixed the connection string the .netcore2.1 test project passed and the Framework 4.7.2 project failed with a different error message

Thus this particular problem appears to have been my connection string.

answered Aug 24 '19 at 22:24

Kirsten

15,730
41
179
318

https://stackoverflow.com/questions/49355530/system-data-sqlclient-is-not-supported-on-this-platform – Kirsten Aug 24 '19 at 22:30
https://stackoverflow.com/questions/57641982/system-platformnotsupportedexception-using-data-sqlclient-sqlconnectionstringbui – Kirsten Aug 24 '19 at 22:37

score 0 · Answer 2 · answered Aug 25 '19 at 00:51

0

This error indicates that the database connection is missing. i think you should stub out the real database layor in unit tests.

answered Aug 25 '19 at 00:51

mayaht

111
2

Could not load file or assembly 'System.ComponentModel.Annotations

2 Answers2