Efcore.pg: .net core 3 preview 6 error: Could not load type 'Microsoft.EntityFrameworkCore.Query.ExpressionTranslators.IMemberTranslator' from assembly 'Microsoft.EntityFrameworkCore.Relational'

[aford22]

Getting the following exception in .net core 3 preview 6:

Could not load type 'Microsoft.EntityFrameworkCore.Query.ExpressionTranslators.IMemberTranslator' from assembly 'Microsoft.EntityFrameworkCore.Relational, Version=3.0.0.0
at
Npgsql.EntityFrameworkCore.PostgreSQL
   at Microsoft.Extensions.DependencyInjection.NpgsqlEntityFrameworkServicesBuilderExtensions.AddEntityFrameworkNpgsql(IServiceCollection serviceCollection)
   at Npgsql.EntityFrameworkCore.PostgreSQL.Infrastructure.Internal.NpgsqlOptionsExtension.ApplyServices(IServiceCollection services)
   at Microsoft.EntityFrameworkCore.Internal.ServiceProviderCache.ApplyServices(IDbContextOptions options, ServiceCollection services)
   at Microsoft.EntityFrameworkCore.Internal.ServiceProviderCache.<>c__DisplayClass4_0.<GetOrAdd>g__BuildServiceProvider|0()
   at Microsoft.EntityFrameworkCore.Internal.ServiceProviderCache.<>c__DisplayClass4_0.<GetOrAdd>b__3(Int64 k)
   at System.Collections.Concurrent.ConcurrentDictionary`2.GetOrAdd(TKey key, Func`2 valueFactory)
   at Microsoft.EntityFrameworkCore.Internal.ServiceProviderCache.GetOrAdd(IDbContextOptions options, Boolean providerRequired)
   at Microsoft.EntityFrameworkCore.DbContext..ctor(DbContextOptions options)
   at OptiCloud.Persistence.DBContext..ctor(DbContextOptions`1 options) in D:\Development\Repos\OptiCloud\OptiCloud.Persistence\DbContext.cs:line 10
   at Microsoft.EntityFrameworkCore.Internal.DbContextPool`1.Rent()
   at Microsoft.EntityFrameworkCore.Internal.DbContextPool`1.Lease..ctor(DbContextPool`1 contextPool)
   at System.RuntimeMethodHandle.InvokeMethod(Object target, Object[] arguments, Signature sig, Boolean constructor, Boolean wrapExceptions)
   at System.Reflection.RuntimeConstructorInfo.Invoke(BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitConstructor(ConstructorCallSite constructorCallSite, RuntimeResolverContext context)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSiteMain(ServiceCallSite callSite, TArgument argument)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitCache(ServiceCallSite callSite, RuntimeResolverContext context, ServiceProviderEngineScope serviceProviderEngine, RuntimeResolverLock lockType)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitScopeCache(ServiceCallSite singletonCallSite, RuntimeResolverContext context)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSite(ServiceCallSite callSite, TArgument argument)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.Resolve(ServiceCallSite callSite, ServiceProviderEngineScope scope)
   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.GetService[T](IServiceProvider provider)
   at Microsoft.Extensions.DependencyInjection.EntityFrameworkServiceCollectionExtensions.<>c__5`2.<AddDbContextPool>b__5_2(IServiceProvider sp)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitFactory(FactoryCallSite factoryCallSite, RuntimeResolverContext context)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSiteMain(ServiceCallSite callSite, TArgument argument)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitCache(ServiceCallSite callSite, RuntimeResolverContext context, ServiceProviderEngineScope serviceProviderEngine, RuntimeResolverLock lockType)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitScopeCache(ServiceCallSite singletonCallSite, RuntimeResolverContext context)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSite(ServiceCallSite callSite, TArgument argument)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitConstructor(ConstructorCallSite constructorCallSite, RuntimeResolverContext context)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSiteMain(ServiceCallSite callSite, TArgument argument)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitCache(ServiceCallSite callSite, RuntimeResolverContext context, ServiceProviderEngineScope serviceProviderEngine, RuntimeResolverLock lockType)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitScopeCache(ServiceCallSite singletonCallSite, RuntimeResolverContext context)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSite(ServiceCallSite callSite, TArgument argument)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.Resolve(ServiceCallSite callSite, ServiceProviderEngineScope scope)
   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.AspNetCore.Components.ComponentFactory.<>c__DisplayClass6_0.<CreateInitializer>b__2(IComponent instance)
   at Microsoft.AspNetCore.Components.ComponentFactory.PerformPropertyInjection(IComponent instance)
   at Microsoft.AspNetCore.Components.ComponentFactory.InstantiateComponent(Type componentType)
   at Microsoft.AspNetCore.Components.Rendering.Renderer.InstantiateChildComponentOnFrame(RenderTreeFrame& frame, Int32 parentComponentId)
   at Microsoft.AspNetCore.Components.RenderTree.RenderTreeDiffBuilder.InitializeNewComponentFrame(DiffContext& diffContext, Int32 frameIndex)
   at Microsoft.AspNetCore.Components.RenderTree.RenderTreeDiffBuilder.InitializeNewSubtree(DiffContext& diffContext, Int32 frameIndex)
   at Microsoft.AspNetCore.Components.RenderTree.RenderTreeDiffBuilder.InsertNewFrame(DiffContext& diffContext, Int32 newFrameIndex)
   at Microsoft.AspNetCore.Components.RenderTree.RenderTreeDiffBuilder.AppendDiffEntriesForRange(DiffContext& diffContext, Int32 oldStartIndex, Int32 oldEndIndexExcl, Int32 newStartIndex, Int32 newEndIndexExcl)
   at Microsoft.AspNetCore.Components.RenderTree.RenderTreeDiffBuilder.ComputeDiff(Renderer renderer, RenderBatchBuilder batchBuilder, Int32 componentId, ArrayRange`1 oldTree, ArrayRange`1 newTree)
   at Microsoft.AspNetCore.Components.Rendering.ComponentState.RenderIntoBatch(RenderBatchBuilder batchBuilder, RenderFragment renderFragment)
   at Microsoft.AspNetCore.Components.Rendering.Renderer.RenderInExistingBatch(RenderQueueEntry renderQueueEntry)
   at Microsoft.AspNetCore.Components.Rendering.Renderer.ProcessRenderQueue()

Does version 3.0.0-preview5 of Npgsql.EntityFrameworkCore.PostgreSQL work with preview 6?

[YohDeadfall]

No, it doesn't. The versions must be equal.

[rszemplinski]

Will there be an update to preview6 anytime soon?

[roji]

Work is currently underway to update to preview7, which should be out very soon. Sorry this is taking long, but 3.0 includes some very significant changes which make the update very non-trivial.

[TomJamesAtDataSummit]

Hi, this post isn't directly related but in my .Net Core 3 solution, I am trying to "Add > New Scaffolded Item... > API Controller with actions, using Entity Framework", which generates an error similar to one listed above. Specifically; "IDbContextOptions" and feel that this is a related issue.

I have installed .Net Core 3 Preview 7, which unfortunately did not resolve the problem. Therefore, I fear that the latest preview has not resolved this.

[roji]

@TomJamesAtDataSummit you'd need to provide more info - your csproj, VS veresion, etc. The error also doesn't seem very related to Npgsql specifically.

[TomJamesAtDataSummit]

It's not Npgsql specific, only a similar reference and error. Does this need to be on a separate thread? Visual studio version:
Microsoft Visual Studio Community 2019
Version 16.2.0
VisualStudio.16.Release/16.2.0+29123.88
Microsoft .NET Framework
Version 4.8.03761

Project details:

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

  <PropertyGroup>
    <TargetFramework>netcoreapp3.0</TargetFramework>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Microsoft.EntityFrameworkCore.Tools" Version="3.0.0-preview7.19362.6">
      <PrivateAssets>all</PrivateAssets>
      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
    </PackageReference>
    <PackageReference Include="Microsoft.Extensions.Logging.Debug" Version="3.0.0-preview7.19362.4" />
    <PackageReference Include="Microsoft.VisualStudio.Web.CodeGeneration.Design" Version="3.0.0-preview7-19378-04" />
  </ItemGroup>

  <ItemGroup>
    <ProjectReference Include="..\Models\Models.csproj" />
  </ItemGroup>

</Project>

[roji]

Yeah, if this isn't Npgsql-related it should definitely be posted in the EF repo, or possibly as a VS issue.

[alien-techno]

Try to install the following package
install-package Microsoft.EntityFrameworkCore.SqlServer

[alien-techno]

I had the similar error but for a different library - the IShapedQueryOptimizerFactory
Could not load type 'Microsoft.EntityFrameworkCore.Query.IShapedQueryOptimizerFactory

I install the following from the package manager console
PM> install-package Microsoft.EntityFrameworkCore.SqlServer

and it resolved the error. Able to run queries using LINQ.
Maybe similar packages exists for this ExpressionTranslator libraries.

[alien-techno]

PM> install-package Microsoft.EntityFrameworkCore.SqlServer

[roji]

@alien-techno you should not need to reference Microsoft.EntityFrameworkCore.SqlServer if you're using Npgsql/PostgreSQL.