dotnet/efcore · error · InvalidOperationException

MemberAccess: Couldn't find symbol for member: {memberAccess

Error message

MemberAccess: Couldn't find symbol for member: {memberAccess}

What it means

VisitMemberAccessExpression throws InvalidOperationException when Roslyn cannot resolve a member access (a.B) to any symbol. The translator needs the member symbol to map it to a reflection PropertyInfo/FieldInfo.

Source

Thrown at src/EFCore.Design/Query/Internal/CSharpToLinqTranslator.cs:772

    /// </summary>
    public override Expression VisitLiteralExpression(LiteralExpressionSyntax literal)
        => _semanticModel.GetTypeInfo(literal) is { ConvertedType: { } type }
            ? Constant(literal.Token.Value, ResolveType(type))
            : Constant(literal.Token.Value);

    /// <summary>
    ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
    ///     the same compatibility standards as public APIs. It may be changed or removed without notice in
    ///     any release. You should only use it directly in your code with extreme caution and knowing that
    ///     doing so can result in application failures when updating to a new Entity Framework Core release.
    /// </summary>
    public override Expression VisitMemberAccessExpression(MemberAccessExpressionSyntax memberAccess)
    {
        var expression = Visit(memberAccess.Expression);

        if (_semanticModel.GetSymbolInfo(memberAccess).Symbol is not { } memberSymbol)
        {
            throw new InvalidOperationException($"MemberAccess: Couldn't find symbol for member: {memberAccess}");
        }

        var containingType = ResolveType(memberSymbol.ContainingType);
        var memberInfo = memberSymbol switch
        {
            IPropertySymbol p => (MemberInfo?)containingType.GetProperty(p.Name),
            IFieldSymbol f => containingType.GetField(f.Name),
            INamedTypeSymbol t => containingType.GetNestedType(t.Name),

            null => throw new InvalidOperationException($"MemberAccess: Couldn't find symbol for member: {memberAccess}"),
            _ => throw new NotSupportedException($"MemberAccess: unsupported member symbol '{memberSymbol.GetType().Name}': {memberAccess}")
        };

        switch (memberInfo)
        {
            case Type nestedType:
                return Constant(nestedType);

View on GitHub (pinned to dbf9771522)

Solutions

Verify the member name and that the containing type is referenced by the precompilation
Make sure the query compiles cleanly in the IDE before precompiling
Remove dynamic member access; use strongly-typed variables

Example fix

// before (typo / unresolved)
var q = ctx.Blogs.Where(b => b.Titel == "x");
// after
var q = ctx.Blogs.Where(b => b.Title == "x");

Defensive patterns

Strategy: validation

Validate before calling

// Ensure the query is error-free in the IDE (Roslyn would otherwise fail to bind the member).
// Confirm the member exists and the containing type is referenced.
var pi = typeof(Entity).GetProperty(nameof(Entity.Title));
if (pi is null) { /* fix typo / add reference */ }

Prevention

Build the project with zero errors/warnings before precompiling queries
Double-check property names for typos
Reference every assembly whose types are accessed in the query

When it happens

Trigger: A member access where GetSymbolInfo(memberAccess).Symbol is null: a typo, a member on an error/unresolved type, dynamic member access, or a member that only exists in an unreferenced assembly.

Common situations: Misspelled property names; accessing members of types from namespaces/assemblies not referenced by the precompilation; accessing members of dynamic-typed expressions.

Related errors

AI-assisted analysis of dotnet/efcore@dbf9771522 (2026-08-06). Data as JSON: /api/errors/edfd8c6c669d6d4e. Report an issue: GitHub.