efcore Read-only property requires explicit ignore when type is derived from `NetTopologySuite.Geometries.GeometryCollection`

Bug description

Having an expression-bodied property with type derived from GeometryCollection worked out of the box in EF Core 8, but requires an explicit ignore in EF Core 9 and later. See exception with stack trace below for what started appearing after upgrading from 8.0.22 to 10.0.0.

This is not a critical issue, as it can be easily resolved by using the NotMapped attribute or calling EntityTypeBuilder.Ignore. But I'm curious as to why the behavior has changed. Is this by design, or a bug? My understanding is that EF Core ignores all expression-bodied properties unless configured otherwise. I've read the breaking changes notes for v9 and v10, but couldn't gather anything relevant from there.

I've provided a very simple example which wouldn't make much sense in production code. I tried to reproduce the issue with my own classes (no NTS), but was unable to do so.

Your code

Program.cs

using Microsoft.EntityFrameworkCore;
using NetTopologySuite.Geometries;

using AppDbContext dbContext = new();

dbContext.Database.GenerateCreateScript();

Console.WriteLine("OK");

public class AppDbContext : DbContext
{
    public DbSet<Shape> Shapes { get; set; }

    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    {
        optionsBuilder.UseSqlServer(string.Empty, o => o.UseNetTopologySuite());
    }
}

public class Shape
{
    public int Id { get; set; }
    public GeometryCollection EmptyCollection => GeometryCollection.Empty;
}


EFCoreNtsTest.csproj - Downgrade package to 8.0.22 and see exception disappears.

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

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net10.0</TargetFramework>
    <ImplicitUsings>enable</ImplicitUsings>
    <Nullable>enable</Nullable>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Microsoft.EntityFrameworkCore.SqlServer.NetTopologySuite" Version="10.0.0" />
  </ItemGroup>

</Project>

Stack traces

System.InvalidOperationException: The property 'Geometry.UserData' could not be mapped because it is of type 'object', which is not a supported primitive type or a valid entity type. Either explicitly map this property, or ignore it using the '[NotMapped]' attribute or by using 'EntityTypeBuilder.Ignore' in 'OnModelCreating'.
   at Microsoft.EntityFrameworkCore.Infrastructure.ModelValidator.ValidatePropertyMapping(IConventionTypeBase structuralType, IConventionModel model, IDiagnosticsLogger`1 logger)
   at Microsoft.EntityFrameworkCore.Infrastructure.ModelValidator.ValidatePropertyMapping(IModel model, IDiagnosticsLogger`1 logger)
   at Microsoft.EntityFrameworkCore.Infrastructure.ModelValidator.Validate(IModel model, IDiagnosticsLogger`1 logger)
   at Microsoft.EntityFrameworkCore.Infrastructure.RelationalModelValidator.Validate(IModel model, IDiagnosticsLogger`1 logger)
   at Microsoft.EntityFrameworkCore.SqlServer.Infrastructure.Internal.SqlServerModelValidator.Validate(IModel model, IDiagnosticsLogger`1 logger)
   at Microsoft.EntityFrameworkCore.Infrastructure.ModelRuntimeInitializer.Initialize(IModel model, Boolean designTime, IDiagnosticsLogger`1 validationLogger)
   at Microsoft.EntityFrameworkCore.Infrastructure.ModelSource.CreateModel(DbContext context, ModelCreationDependencies modelCreationDependencies, Boolean designTime)
   at Microsoft.EntityFrameworkCore.Infrastructure.ModelSource.GetModel(DbContext context, ModelCreationDependencies modelCreationDependencies, Boolean designTime)
   at Microsoft.EntityFrameworkCore.Internal.DbContextServices.CreateModel(Boolean designTime)
   at Microsoft.EntityFrameworkCore.Internal.DbContextServices.get_Model()
   at Microsoft.EntityFrameworkCore.Infrastructure.EntityFrameworkServicesBuilder.<>c.<TryAddCoreServices>b__8_4(IServiceProvider p)
   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 callSite, 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 callSite, 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 callSite, 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 callSite, 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 callSite, 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 callSite, 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__DisplayClass2_0.<RealizeService>b__0(ServiceProviderEngineScope scope)
   at Microsoft.Extensions.DependencyInjection.ServiceProvider.GetService(ServiceIdentifier serviceIdentifier, 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_ContextServices()
   at Microsoft.EntityFrameworkCore.DbContext.get_InternalServiceProvider()
   at Microsoft.EntityFrameworkCore.DbContext.Microsoft.EntityFrameworkCore.Infrastructure.IInfrastructure<System.IServiceProvider>.get_Instance()
   at Microsoft.EntityFrameworkCore.Infrastructure.DatabaseFacade.Microsoft.EntityFrameworkCore.Infrastructure.IInfrastructure<System.IServiceProvider>.get_Instance()
   at Microsoft.EntityFrameworkCore.RelationalDatabaseFacadeExtensions.GetRelationalService[TService](IInfrastructure`1 databaseFacade)
   at Microsoft.EntityFrameworkCore.RelationalDatabaseFacadeExtensions.GenerateCreateScript(DatabaseFacade databaseFacade)
   at Program.<Main>$(String[] args) in Program.cs:line 6

Verbose output

EF Core version

10.0.0

Database provider

No response

Target framework

.NET 10

Operating system

No response

IDE

VS Code 1.106.3

Nov 30 '25 23:11 palhal

My understanding is that EF Core ignores all expression-bodied properties unless configured otherwise.

That's not accurate - EF cannot even know whether a property is expression-bodied or not; expression-bodied properties are purely a C# syntactical thing and compile to the same thing as regular properties.

The actual behavior is that EF is supposed to ignore read-only properties (properties without a setter) by default, regardless of whether they're expression-bodied or not. And there indeed seems to be a validation issue here; note that the error message isn't on the GeometryCollection property itself, but rather on the UserData property nested within it (if you swap GeometryCollection for another type without problematic properties on it, the property does get properly ignored).

Dec 01 '25 08:12 roji

@AndriySvyryd assigning to you but putting in the backlog as this doesn't seem high-priority (but feel free to change of course).

Dec 01 '25 08:12 roji

That's not accurate - EF cannot even know whether a property is expression-bodied or not; expression-bodied properties are purely a C# syntactical thing and compile to the same thing as regular properties.

Yes, that makes perfect sense, and I was wondering how you could distinguish between the two. While writing this report, I noticed that I had some { get; } properties that were read from the database, but I forgot that PropertyBuilder.ValueGeneratedOnAdd was called for them.

note that the error message isn't on the GeometryCollection property itself, but rather on the UserData property nested within it (if you swap GeometryCollection for another type without problematic properties on it, the property does get properly ignored).

Yes, it's the property of the Geometry class that isn't properly ignored, and to be honest I have no idea of what's going on here. I don't know if it helps, but I've also found out that:

Having a read-only property of LineString works (inherits from Geometry)
Having a read-only property of MultiLineString fails (inherits from GeometryCollection)
Having a read-only property of IEnumerable<Geometry> fails

Dec 01 '25 13:12 palhal