.NET 6 breaks EF Core 2.2

[YwVaske]

Describe the bug

Entity Framework 2.2 breaks when using .NET 6.
I know that EF Core 2.2 is not supported anymore, but i hope this bug can still be fixed, because .NET 6 breaks it (While .NET 5 still works with the same code).
We at our company unfortunately cannot update our EF Core version yet.

To Reproduce

I've created a very little repository that demonstrates the Bug. The Repository contains a EF Core Example and 2 calling Projects (one in .NET 5 and one .NET 6). With exactly the same code, .NET 6 fails with an Exception.
https://github.com/DrVaskee/DotNet6BreaksEfCore2

Exceptions (if any)

In .NET 6 the following exception is thrown:

Unhandled exception. System.TypeInitializationException: The type initializer for 'Microsoft.EntityFrameworkCore.Query.ResultOperators.Internal.TrackingExpressionNode' threw an exception.
 ---> System.TypeInitializationException: The type initializer for 'Microsoft.EntityFrameworkCore.EntityFrameworkQueryableExtensions' threw an exception.
 ---> System.InvalidOperationException: Sequence contains more than one matching element
   at System.Linq.ThrowHelper.ThrowMoreThanOneMatchException()
   at System.Linq.Enumerable.TryGetSingle[TSource](IEnumerable`1 source, Func`2 predicate, Boolean& found)
   at System.Linq.Enumerable.Single[TSource](IEnumerable`1 source, Func`2 predicate)
   at Microsoft.EntityFrameworkCore.EntityFrameworkQueryableExtensions.GetMethod(String name, Int32 parameterCount, Func`2 predicate)
   at Microsoft.EntityFrameworkCore.EntityFrameworkQueryableExtensions..cctor()
   --- End of inner exception stack trace ---
   at Microsoft.EntityFrameworkCore.Query.ResultOperators.Internal.TrackingExpressionNode..cctor()
   --- End of inner exception stack trace ---
   at Microsoft.EntityFrameworkCore.Query.Internal.MethodInfoBasedNodeTypeRegistryFactory..ctor(MethodInfoBasedNodeTypeRegistry methodInfoBasedNodeTypeRegistry)
   at Microsoft.EntityFrameworkCore.Query.Internal.DefaultMethodInfoBasedNodeTypeRegistryFactory..ctor()
   at System.RuntimeType.CreateInstanceDefaultCtor(Boolean publicOnly, Boolean wrapExceptions)
--- End of stack trace from previous location ---
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitCreateInstance(CreateInstanceCallSite createInstanceCallSite, 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.CallSiteRuntimeResolver.VisitSingleton(SingletonCallSite singletonCallSite, 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.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.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.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.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.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.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.CallSiteRuntimeResolver.Resolve(IServiceCallSite 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.InMemoryServiceCollectionExtensions.<>c.<AddEntityFrameworkInMemoryDatabase>b__0_0(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.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.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.CallSiteRuntimeResolver.Resolve(IServiceCallSite 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.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.EntryWithoutDetectChanges[TEntity](TEntity entity)
   at Microsoft.EntityFrameworkCore.DbContext.SetEntityState[TEntity](TEntity entity, EntityState entityState)
   at Microsoft.EntityFrameworkCore.DbContext.Add[TEntity](TEntity entity)
   at EfLogic.Test.DoStuff() in /Volumes/temp/DotNet6BreaksEfCore2/EfLogic/Test.cs:line 12
   at Program.<Main>$(String[] args) in /Volumes/temp/DotNet6BreaksEfCore2/Net6Project/Program.cs:line 5

Further technical details

• dotnet --info Output:

.NET SDK (reflecting any global.json):
 Version:   6.0.100
 Commit:    9e8b04bbff

Runtime Environment:
 OS Name:     Mac OS X
 OS Version:  12.0
 OS Platform: Darwin
 RID:         osx-x64
 Base Path:   /usr/local/share/dotnet/sdk/6.0.100/

Host (useful for support):
  Version: 6.0.0
  Commit:  4822e3c3aa

.NET SDKs installed:
  2.2.207 [/usr/local/share/dotnet/sdk]
  3.1.413 [/usr/local/share/dotnet/sdk]
  5.0.400 [/usr/local/share/dotnet/sdk]
  6.0.100 [/usr/local/share/dotnet/sdk]

.NET runtimes installed:
  Microsoft.AspNetCore.All 2.2.8 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.App 2.2.8 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 3.1.19 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 5.0.9 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 6.0.0 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 2.2.8 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
  Microsoft.NETCore.App 3.1.19 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
  Microsoft.NETCore.App 5.0.9 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
  Microsoft.NETCore.App 6.0.0 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]

• I use Jetbrains Rider on MacOs (Intel Mac), but the same exception occures either in commandline, Visual Studio and on Windows 10.

I couldn't figure out the best area label to add to this issue. If you have write-permissions please help me learn by adding exactly one area label.

[KalleOlaviNiemitalo]

#24002 seems to describe this problem. I don't think it is feasible to fix it by modifying .NET SDK or .NET Runtime. If you really cannot upgrade Entity Framework, I think you must either avoid upgrading to .NET 6, or fork EF 2.2 and backport the fix to that yourself.

[YwVaske]

Alright.
Because EF.Core 6 ist not compatible with .NET Framework Versions, we have to stick with EF.Core 2 for at least a few months.
So i said to myself, how hard could it be to fork and patch it myself.

The documentation on "how to build from source" is not working anymore. I mean the "2.x or older" section hasn't been updated.

It is not possible to restore nuget packages on that old source code. Some nuget feeds point to e.g. "https://dotnet.myget.org/F/dotnet-core/api/v3/index.json" which seems to be offline by now.

Also it tells me that the Package "Internal.AspNetCore.Sdk" is missing. A package i have never heard of before. A quick search on that topic didn't help either. The documentation isn't mentioning it either.

It's sad, that it's not possible to download old source and compile it, because references are missing.

Is there any chance to get it running again?

[ajcvickers]

@DrVaskee We will not be fixing this in 2.2 because 2.2 is no longer supported. You should be able to build 2.2, but I expect you'll need the full 2.2 SDK installed on your machine. However, no guarantees, since 2.2 has been out of support for quite some time, so we haven't built it recently, and a lot of the build infrastructure has changed significantly.

[YwVaske]

Thank you anyway.
I was kinda expecting this answer.
I do however have the full 2.2 SDK installed. But it is always telling me, that it can't find "Internal.AspNetCore.Sdk".

I'll keep trying...

[napernik]

I've made a workaround using Harmony, that allows running EF 2.2.6 on .NET 7 (hasn't been tried on other versions)

The fix targets the static constructors for EntityFrameworkQueryableExtensions and LinqOperatorProvider classes.

Usage:

1. Install a NuGet package: Lib.Harmony version 2.2.2
2. Call EntityFrameworkCorePatch.Apply() in startup

Source code:

using System.Linq.Expressions;
using System.Reflection;
using System.Reflection.Emit;

using Microsoft.EntityFrameworkCore;

using HarmonyLib;
using Microsoft.EntityFrameworkCore.Query.ResultOperators.Internal;
using Microsoft.EntityFrameworkCore.Query.Internal;

namespace XXXXX
{
	/// <summary>
	/// Applies a workaround for the issue that breaks Entity Framework Core 2.2.x on .NET 6 and higher.
	/// https://github.com/dotnet/efcore/issues/26950
	/// </summary>
	public static class EntityFrameworkCorePatch
	{
		private static readonly Harmony _harmony = new Harmony("Emply.efCorePatch");

		public static MethodInfo Patched_EntityFrameworkQueryableExtensions_GetMethod(string name, int parameterCount = 0, Func<MethodInfo, bool> predicate = null)
		{
			// Custom fix: begin
			if ((name is nameof(Queryable.FirstOrDefault)
						or nameof(Queryable.LastOrDefault)
						or nameof(Queryable.SingleOrDefault)
						or nameof(Queryable.Min)
						or nameof(Queryable.Max))
				&& parameterCount == 1)
			{
				return typeof(Queryable).GetTypeInfo().GetDeclaredMethods(name)
								.Single(mi => mi.GetParameters().Length == parameterCount + 1
										  && mi.GetParameters().Last().ParameterType.Name.StartsWith(nameof(Expression))
										  && (predicate == null || predicate(mi)));
			}
			// Custom fix: end

			return typeof(Queryable).GetTypeInfo().GetDeclaredMethods(name)
				.Single(mi => mi.GetParameters().Length == parameterCount + 1
						  && (predicate == null || predicate(mi)));
		}

		public static MethodInfo Patched_LinqOperatorProvider_GetMethod(string name, int parameterCount = 0)
		{
			return Patched_LinqOperatorProvider_GetMethods(name, parameterCount).Single();
		}

		public static IEnumerable<MethodInfo> Patched_LinqOperatorProvider_GetMethods(string name, int parameterCount = 0)
		{
			// Custom fix: begin
			if (name == nameof(Enumerable.Take) && parameterCount == 1)
			{
				return typeof(Enumerable).GetTypeInfo().GetDeclaredMethods(name)
						.Where(mi => mi.GetParameters().Length == parameterCount + 1
									&& mi.GetParameters().Last().ParameterType == typeof(int));
			}
			// Custom fix: end

			return typeof(Enumerable).GetTypeInfo().GetDeclaredMethods(name)
				.Where(mi => mi.GetParameters().Length == parameterCount + 1);
		}

		public static IEnumerable<CodeInstruction> EntityFrameworkQueryableExtensions_CctorTranspiler(IEnumerable<CodeInstruction> instructions)
		{
			MethodInfo patchedGetMethodMethod = typeof(EntityFrameworkCorePatch)
				.GetMethod(nameof(Patched_EntityFrameworkQueryableExtensions_GetMethod), BindingFlags.Public | BindingFlags.Static);


			bool found = false;
			foreach (CodeInstruction instruction in instructions)
			{
				if (instruction.operand is MethodInfo methodInfo
					&& methodInfo.Name == "GetMethod"
					&& !methodInfo.IsGenericMethod)
				{
					CodeInstruction newInstruction = new CodeInstruction(OpCodes.Call, patchedGetMethodMethod);
					yield return newInstruction;
					found = true;
				}
				else
				{
					yield return instruction;
				}
			}

			if (!found)
			{
				throw new InvalidOperationException("Failed to find a call to GetMethod()");
			}
		}

		public static IEnumerable<CodeInstruction> LinqOperatorProvider_CctorTranspiler(IEnumerable<CodeInstruction> instructions)
		{
			MethodInfo patchedGetMethodMethod = typeof(EntityFrameworkCorePatch)
				.GetMethod(nameof(Patched_LinqOperatorProvider_GetMethod), BindingFlags.Public | BindingFlags.Static);

			bool found = false;
			foreach (CodeInstruction instruction in instructions)
			{
				if (instruction.operand is MethodInfo methodInfo
					&& methodInfo.Name == "GetMethod"
					&& !methodInfo.IsGenericMethod)
				{
					CodeInstruction newInstruction = new CodeInstruction(OpCodes.Call, patchedGetMethodMethod);
					yield return newInstruction;
					found = true;
				}
				else
				{
					yield return instruction;
				}
			}

			if (!found)
			{
				throw new InvalidOperationException("Failed to find a call to GetMethod()");
			}
		}

		private static void Patch_EntityFrameworkQueryableExtensions()
		{
			MethodBase mOriginal = typeof(EntityFrameworkQueryableExtensions).TypeInitializer;

			MethodInfo transpiler = typeof(EntityFrameworkCorePatch)
				.GetMethod(nameof(EntityFrameworkQueryableExtensions_CctorTranspiler), BindingFlags.Public | BindingFlags.Static);

			_harmony.Patch(mOriginal, transpiler: new HarmonyMethod(transpiler));
		}

		private static void Patch_LinqOperatorProvider()
		{
			MethodBase mOriginal = typeof(LinqOperatorProvider).TypeInitializer;

			MethodInfo transpiler = typeof(EntityFrameworkCorePatch)
				.GetMethod(nameof(LinqOperatorProvider_CctorTranspiler), BindingFlags.Public | BindingFlags.Static);

			_harmony.Patch(mOriginal, transpiler: new HarmonyMethod(transpiler));
		}

		public static void Apply()
		{
			Patch_EntityFrameworkQueryableExtensions();
			Patch_LinqOperatorProvider();

			// Test1: Invoking the static constructor for EntityFrameworkQueryableExtensions indirectly
			TrackingExpressionNode.SupportedMethods.ToList();

			// Test2: Invoking the static constructor for LinqOperatorProvider
			MethodInfo take = new LinqOperatorProvider().Take;
		}
	}
}

[mbileya]

@napernik - Thanks a lot for this man!!! A year later an you're still saving people's lives!!! BTW - Lib.Harmony version 2.3.3 works with .net 8.