Entity with shadow property and nullable complex property with discriminator throws ArgumentOutOfRangeException when queried

[peterwurzinger]

Bug description

When configuring an entity that contains both

• a nullable complex property needing a discriminator and
• a shadow property

querying tracked instances of the configured entity throws an ArgumentOutOfRangeException. A quick inspection with Source Link indicates, that it somehow seems to lose track of the Discriminator property in ShadowValuesFactoryFactory.CreateReadShadowValueExpression, as only the manually configured shadow properties are present.

For context:
I encountered the problem with a real-life complex property that consisted of optional/nullable properties only, in combination with an entity-level Audit that would be applied to entities meeting a certain criteria by convention. So the use case is not too exotic.

I tried to reproduce it as concise as possible using the InMemory provider, but I observed the problem with the SqlServer provider as well. I think it's a provider-agnostic issue anyways.

Your code

#:package Microsoft.EntityFrameworkCore.InMemory@10.0.1
#:property PublishAot=false

using Microsoft.EntityFrameworkCore;

await using var context = new EntityContext();
await context.Database.EnsureCreatedAsync();

//Throws ArgumentOutOfRangeException
var entities = await context.Entities.ToArrayAsync();

public class EntityContext : DbContext
{
  protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    => optionsBuilder.UseInMemoryDatabase("ComplexPropertyRepro");

  public DbSet<Entity> Entities { get; set; }
  protected override void OnModelCreating(ModelBuilder modelBuilder)
  {
    var entity = modelBuilder.Entity<Entity>();
    entity.Property(p => p.Id);
    entity.HasKey(p => p.Id);

    var compl = entity.ComplexProperty(p => p.Prop);
    compl.Property(p => p.OptionalValue);
    compl.HasDiscriminator();

    //Imagine this being added via convetion to prepare some kind of entity-level audit
    entity.Property<string>("CreatedBy").IsRequired(false);
  }
}

public class Entity
{
  public Guid Id { get; set; }
  public OptionalComplexProperty? Prop { get; set; }
}

public class OptionalComplexProperty
{
  public bool? OptionalValue { get; set; }
}

Stack traces

Unhandled exception. System.ArgumentOutOfRangeException: Index was out of range. Must be non-negative and less than the size of the collection. (Parameter 'index')
   at System.SZArrayHelper.get_Item[T](Int32 index)
   at Microsoft.EntityFrameworkCore.ChangeTracking.Internal.ShadowValuesFactoryFactory.CreateReadShadowValueExpression(Expression parameter, IPropertyBase property)
   at Microsoft.EntityFrameworkCore.ChangeTracking.Internal.ShadowValuesFactoryFactory.CreateReadValueExpression(Expression parameter, IPropertyBase property)
   at Microsoft.EntityFrameworkCore.ChangeTracking.Internal.SnapshotFactoryFactory.CreateSnapshotExpression(Type clrType, Expression parameter, Type[] types, IList`1 propertyBases)
   at Microsoft.EntityFrameworkCore.ChangeTracking.Internal.SnapshotFactoryFactory.CreateConstructorExpression(IRuntimeTypeBase structuralType, Expression parameter)
   at Microsoft.EntityFrameworkCore.Query.ShapedQueryCompilingExpressionVisitor.StructuralTypeMaterializerInjector.CreateFullMaterializeExpression(ITypeBase concreteStructuralType, ValueTuple`5 materializeExpressionContext)
   at Microsoft.EntityFrameworkCore.Query.ShapedQueryCompilingExpressionVisitor.StructuralTypeMaterializerInjector.MaterializeEntity(StructuralTypeShaperExpression shaper, ParameterExpression materializationContextVariable, ParameterExpression concreteEntityTypeVariable, ParameterExpression instanceVariable, ParameterExpression entryVariable)
   at Microsoft.EntityFrameworkCore.Query.ShapedQueryCompilingExpressionVisitor.StructuralTypeMaterializerInjector.ProcessStructuralTypeShaper(StructuralTypeShaperExpression shaper)
   at Microsoft.EntityFrameworkCore.Query.ShapedQueryCompilingExpressionVisitor.StructuralTypeMaterializerInjector.VisitExtension(Expression extensionExpression)
   at Microsoft.EntityFrameworkCore.Query.ShapedQueryCompilingExpressionVisitor.StructuralTypeMaterializerInjector.Inject(Expression expression)
   at Microsoft.EntityFrameworkCore.Query.ShapedQueryCompilingExpressionVisitor.InjectStructuralTypeMaterializers(Expression expression)
   at Microsoft.EntityFrameworkCore.InMemory.Query.Internal.InMemoryShapedQueryCompilingExpressionVisitor.ShaperExpressionProcessingExpressionVisitor.VisitExtension(Expression extensionExpression)
   at Microsoft.EntityFrameworkCore.InMemory.Query.Internal.InMemoryShapedQueryCompilingExpressionVisitor.ShaperExpressionProcessingExpressionVisitor.ProcessShaper(Expression shaperExpression)
   at Microsoft.EntityFrameworkCore.InMemory.Query.Internal.InMemoryShapedQueryCompilingExpressionVisitor.VisitShapedQuery(ShapedQueryExpression shapedQueryExpression)
   at Microsoft.EntityFrameworkCore.Query.ShapedQueryCompilingExpressionVisitor.VisitExtension(Expression extensionExpression)
   at Microsoft.EntityFrameworkCore.InMemory.Query.Internal.InMemoryShapedQueryCompilingExpressionVisitor.VisitExtension(Expression extensionExpression)
   at Microsoft.EntityFrameworkCore.Query.QueryCompilationContext.CreateQueryExecutorExpression[TResult](Expression query)
   at Microsoft.EntityFrameworkCore.Query.QueryCompilationContext.CreateQueryExecutor[TResult](Expression query)
   at Microsoft.EntityFrameworkCore.Storage.Database.CompileQuery[TResult](Expression query, Boolean async)
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.CompileQueryCore[TResult](IDatabase database, Expression query, IModel model, Boolean async)
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.<>c__DisplayClass11_0`1.<ExecuteCore>b__0()
   at Microsoft.EntityFrameworkCore.Query.Internal.CompiledQueryCache.GetOrAddQuery[TResult](Object cacheKey, Func`1 compiler)
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.ExecuteCore[TResult](Expression query, Boolean async, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.ExecuteAsync[TResult](Expression query, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.Query.Internal.EntityQueryProvider.ExecuteAsync[TResult](Expression expression, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.Query.Internal.EntityQueryable`1.GetAsyncEnumerator(CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.Internal.InternalDbSet`1.System.Collections.Generic.IAsyncEnumerable<TEntity>.GetAsyncEnumerator(CancellationToken cancellationToken)
   at System.Runtime.CompilerServices.ConfiguredCancelableAsyncEnumerable`1.GetAsyncEnumerator()
   at Microsoft.EntityFrameworkCore.EntityFrameworkQueryableExtensions.ToListAsync[TSource](IQueryable`1 source, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.EntityFrameworkQueryableExtensions.ToArrayAsync[TSource](IQueryable`1 source, CancellationToken cancellationToken)
   at Program.<Main>$(String[] args) in E:\ComplexPropertyRepro\Program.cs:line 10
   at Program.<Main>$(String[] args) in E:\ComplexPropertyRepro\Program.cs:line 10
   at Program.<Main>(String[] args)

Verbose output

EF Core version

10.0.1

Database provider

Microsoft.EntityFrameworkCore.SqlServer and Microsoft.EntityFrameworkCore.InMemory

Target framework

net10.0

Operating system

Windows 11

IDE

Visual Studio 2026 and .NET SDK on CLI