Migration from EF Core 3.1 to 5 - Using property Count in IReadOnlyCollection throws NullReferenceException

[Airfolen]

Example repository

https://github.com/Airfolen/Reproducing_EF_Core_5_Error

Code

 public class Author
    {
        public int AuthorId { get; set; }
        public string FirstName { get; set; }
        public string LastName { get; set; }
        public IReadOnlyCollection<Book> Books { get; set; }
    }

...

 await using (var context = new DemonstrationDbContext())
{
    var correctBooksCounts = await context.Authors
        .Select(a => new
        {
            BooksCount = a.Books.Count() // its ok
        }).ToListAsync();
    
    var incorrectBooksCounts = await context.Authors
        .Select(a => new
        {
            BooksCount = a.Books.Count // NullReferenceException
        }).ToListAsync();
}

Stack traces

 System.NullReferenceException: Object reference not set to an instance of an object.
   at Microsoft.EntityFrameworkCore.Query.SqlExpressions.SelectExpression.ApplyCollectionJoin(Int32 collectionIndex, Int32 collectionId, Expression innerShaper, INavigationBase naviga
tion, Type elementType, Boolean splitQuery)
   at Microsoft.EntityFrameworkCore.Query.Internal.CollectionJoinApplyingExpressionVisitor.VisitExtension(Expression extensionExpression)
   at System.Linq.Expressions.Expression.Accept(ExpressionVisitor visitor)
   at System.Linq.Expressions.ExpressionVisitor.Visit(Expression node)
   at System.Linq.Expressions.ExpressionVisitor.VisitMember(MemberExpression node)
   at System.Linq.Expressions.MemberExpression.Accept(ExpressionVisitor visitor)
   at System.Linq.Expressions.ExpressionVisitor.Visit(Expression node)
   at System.Linq.Expressions.ExpressionVisitor.VisitUnary(UnaryExpression node)
   at System.Linq.Expressions.UnaryExpression.Accept(ExpressionVisitor visitor)
   at System.Linq.Expressions.ExpressionVisitor.Visit(Expression node)
   at System.Linq.Expressions.ExpressionVisitor.VisitConditional(ConditionalExpression node)
   at System.Linq.Expressions.ConditionalExpression.Accept(ExpressionVisitor visitor)
   at System.Linq.Expressions.ExpressionVisitor.Visit(Expression node)
   at System.Linq.Expressions.ExpressionVisitor.VisitUnary(UnaryExpression node)
   at System.Linq.Expressions.UnaryExpression.Accept(ExpressionVisitor visitor)
   at System.Linq.Expressions.ExpressionVisitor.Visit(Expression node)
   at System.Dynamic.Utils.ExpressionVisitorUtils.VisitArguments(ExpressionVisitor visitor, IArgumentProvider nodes)
   at System.Linq.Expressions.ExpressionVisitor.VisitNew(NewExpression node)
   at System.Linq.Expressions.NewExpression.Accept(ExpressionVisitor visitor)
   at System.Linq.Expressions.ExpressionVisitor.Visit(Expression node)
   at Microsoft.EntityFrameworkCore.Query.Internal.CollectionJoinApplyingExpressionVisitor.VisitExtension(Expression extensionExpression)
   at System.Linq.Expressions.Expression.Accept(ExpressionVisitor visitor)
   at System.Linq.Expressions.ExpressionVisitor.Visit(Expression node)
   at Microsoft.EntityFrameworkCore.Query.RelationalQueryTranslationPostprocessor.Process(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__DisplayClass12_0`1.<ExecuteAsync>b__0()
   at Microsoft.EntityFrameworkCore.Query.Internal.CompiledQueryCache.GetOrAddQuery[TResult](Object cacheKey, Func`1 compiler)
   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 System.Runtime.CompilerServices.ConfiguredCancelableAsyncEnumerable`1.GetAsyncEnumerator()
   at Microsoft.EntityFrameworkCore.EntityFrameworkQueryableExtensions.ToListAsync[TSource](IQueryable`1 source, CancellationToken cancellationToken)
   at Reproducing_EF_Core_5_Error.Program.Main(String[] args) in C:\Users\Airfolen\RiderProjects\BCS\BCS Test Projects\Reproducing_EF_Core_5_Error\Reproducing_EF_Core_5_Error\Program.
cs:line 46
   at Reproducing_EF_Core_5_Error.Program.Main(String[] args) in C:\Users\Airfolen\RiderProjects\BCS\BCS Test Projects\Reproducing_EF_Core_5_Error\Reproducing_EF_Core_5_Error\Program.
cs:line 51
   at Reproducing_EF_Core_5_Error.Program.<Main>(String[] args)

Provider and version information

EF Core version:
Database provider: (e.g. Npgsql.EntityFrameworkCore.PostgreSQL 5.0.0)
Target framework: (e.g. .NET 5.0)

[ajcvickers]

Note for triage: still repros on 6.0 daily. Issue is using Count property on IReadOnlyCollection--ICollection.Count works.

Unhandled exception. System.ArgumentException: GenericArguments[1], 'System.Collections.Generic.IReadOnlyCollection`1[Reproducing_EF_Core_5_Error.Database.Book]', on 'TCollection InitializeCollection[TElement,TCollection](Int32, Microsoft.EntityFrameworkCore.Query.QueryContext, System.Data.Common.DbDataReade
r, Microsoft.EntityFrameworkCore.Query.Internal.SingleQueryResultCoordinator, System.Func`3[Microsoft.EntityFrameworkCore.Query.QueryContext,System.Data.Common.DbDataReader,System.Object[]], System.Func`3[Microsoft.EntityFrameworkCore.Query.QueryContext,System.Data.Common.DbDataReader,System.Object[]], Micro
soft.EntityFrameworkCore.Metadata.IClrCollectionAccessor)' violates the constraint of type 'TCollection'.
 ---> System.Security.VerificationException: Method Microsoft.EntityFrameworkCore.Query.RelationalShapedQueryCompilingExpressionVisitor+ShaperProcessingExpressionVisitor.InitializeCollection: type argument 'System.Collections.Generic.IReadOnlyCollection`1[Reproducing_EF_Core_5_Error.Database.Book]' violates
the constraint of type parameter 'TCollection'.
   at System.RuntimeMethodHandle.GetStubIfNeeded(RuntimeMethodHandleInternal method, RuntimeType declaringType, RuntimeType[] methodInstantiation)
   at System.Reflection.RuntimeMethodInfo.MakeGenericMethod(Type[] methodInstantiation)
   --- End of inner exception stack trace ---
   at System.RuntimeType.ValidateGenericArguments(MemberInfo definition, RuntimeType[] genericArguments, Exception e)
   at System.Reflection.RuntimeMethodInfo.MakeGenericMethod(Type[] methodInstantiation)
   at Microsoft.EntityFrameworkCore.Query.RelationalShapedQueryCompilingExpressionVisitor.ShaperProcessingExpressionVisitor.VisitExtension(Expression extensionExpression)
   at System.Linq.Expressions.Expression.Accept(ExpressionVisitor visitor)
   at System.Linq.Expressions.ExpressionVisitor.Visit(Expression node)
   at System.Linq.Expressions.ExpressionVisitor.VisitBinary(BinaryExpression node)
   at Microsoft.EntityFrameworkCore.Query.RelationalShapedQueryCompilingExpressionVisitor.ShaperProcessingExpressionVisitor.VisitBinary(BinaryExpression binaryExpression)
   at System.Linq.Expressions.BinaryExpression.Accept(ExpressionVisitor visitor)
   at System.Linq.Expressions.ExpressionVisitor.Visit(Expression node)
   at System.Linq.Expressions.ExpressionVisitor.VisitConditional(ConditionalExpression node)
   at System.Linq.Expressions.ConditionalExpression.Accept(ExpressionVisitor visitor)
   at System.Linq.Expressions.ExpressionVisitor.Visit(Expression node)
   at System.Linq.Expressions.ExpressionVisitor.VisitUnary(UnaryExpression node)
   at System.Linq.Expressions.UnaryExpression.Accept(ExpressionVisitor visitor)
   at System.Linq.Expressions.ExpressionVisitor.Visit(Expression node)
   at System.Dynamic.Utils.ExpressionVisitorUtils.VisitArguments(ExpressionVisitor visitor, IArgumentProvider nodes)
   at System.Linq.Expressions.ExpressionVisitor.VisitNew(NewExpression node)
   at System.Linq.Expressions.NewExpression.Accept(ExpressionVisitor visitor)
   at System.Linq.Expressions.ExpressionVisitor.Visit(Expression node)
   at Microsoft.EntityFrameworkCore.Query.RelationalShapedQueryCompilingExpressionVisitor.ShaperProcessingExpressionVisitor.ProcessShaper(Expression shaperExpression, RelationalCommandCache& relationalCommandCache, LambdaExpression& relatedDataLoaders, Int32& collectionId)
   at Microsoft.EntityFrameworkCore.Query.RelationalShapedQueryCompilingExpressionVisitor.VisitShapedQuery(ShapedQueryExpression shapedQueryExpression)
   at Microsoft.EntityFrameworkCore.Query.ShapedQueryCompilingExpressionVisitor.VisitExtension(Expression extensionExpression)
   at System.Linq.Expressions.Expression.Accept(ExpressionVisitor visitor)
   at System.Linq.Expressions.ExpressionVisitor.Visit(Expression node)
   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__DisplayClass12_0`1.<ExecuteAsync>b__0()
   at Microsoft.EntityFrameworkCore.Query.Internal.CompiledQueryCache.GetOrAddQuery[TResult](Object cacheKey, Func`1 compiler)
   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 System.Runtime.CompilerServices.ConfiguredCancelableAsyncEnumerable`1.GetAsyncEnumerator()
   at Microsoft.EntityFrameworkCore.EntityFrameworkQueryableExtensions.ToListAsync[TSource](IQueryable`1 source, CancellationToken cancellationToken)
   at Reproducing_EF_Core_5_Error.Program.Main(String[] args) in C:\local\code\repros\Reproducing_EF_Core_5_Error-master\Reproducing_EF_Core_5_Error-master\Reproducing_EF_Core_5_Error\Program.cs:line 44
   at Reproducing_EF_Core_5_Error.Program.Main(String[] args) in C:\local\code\repros\Reproducing_EF_Core_5_Error-master\Reproducing_EF_Core_5_Error-master\Reproducing_EF_Core_5_Error\Program.cs:line 49
   at Reproducing_EF_Core_5_Error.Program.<Main>(String[] args)