dotnet/efcore · error · InvalidOperationException

Couldn't find type symbol for: {type}

Error message

Couldn't find type symbol for: {type}

What it means

Thrown in PrecompiledQueryCodeGenerator.GetTypeSymbol (line 1287) when a runtime System.Type's FullName cannot be resolved by compilation.GetTypeByMetadataName. After handling arrays and constructed generics, GetTypeSymbol falls back to looking the type up by its FullName in the analysis compilation; if that returns null it throws InvalidOperationException. The type is not visible to the Roslyn compilation performing code generation.

Source

Thrown at src/EFCore.Design/Query/Internal/PrecompiledQueryCodeGenerator.cs:1287

            return compilation.CreateArrayTypeSymbol(elementSymbol, type.GetArrayRank());
        }

        if (type.IsGenericType && !type.IsGenericTypeDefinition)
        {
            var genericDefinition = (INamedTypeSymbol)GetTypeSymbol(
                compilation,
                type.GetGenericTypeDefinition());

            var typeArguments = type
                .GetGenericArguments()
                .Select(t => GetTypeSymbol(compilation, t))
                .ToArray();

            return genericDefinition.Construct(typeArguments);
        }

        return type.FullName is null || compilation.GetTypeByMetadataName(type.FullName) is not { } typeSymbol
            ? throw new InvalidOperationException($"Couldn't find type symbol for: {type}")
            : typeSymbol;
    }

    [return: NotNullIfNotNull(nameof(name))]
    private static string? SanitizeIdentifierName(string? name)
    {
        if (name == null)
        {
            return null;
        }

        if (string.IsNullOrWhiteSpace(name))
        {
            return "_";
        }

        var result = new string(
            [.. name.Select(c => SyntaxFacts.IsIdentifierPartCharacter(c) ? c : '_')]);

View on GitHub (pinned to dbf9771522)

Solutions

1. Add the missing assembly reference to the project so the type is visible to the analysis compilation.
2. Ensure any source-generated types are generated before precompiled-query analysis runs (check generator ordering / build target).
3. Replace the unresolvable type with a concrete, named type defined in a referenced assembly.
4. Clean and rebuild to refresh the analyzer's view of referenced assemblies.

// Confirm the type is resolvable in the compilation before generating
if (type.FullName is null || compilation.GetTypeByMetadataName(type.FullName) is null)
{ /* add missing reference or exclude query */ }

try { /* generate */ }
catch (InvalidOperationException ex) when (ex.Message.StartsWith("Couldn't find type symbol"))
{ /* add the missing assembly reference, then retry */ }

When it happens

Trigger: Precompiling a query that references a type (entity, value, or parameter type) whose assembly is not referenced by the Roslyn Compilation, or whose FullName is null (e.g. an anonymous type used in an unsupported position, a nested type with an unspeakable name, or a type from an unloaded assembly). GetTypeSymbol returns null from GetTypeByMetadataName and throws.

Common situations: The project being analyzed is missing a reference to the assembly that defines a type used in the query. The type lives in a source-generated assembly not yet produced when the analyzer runs. A type with no resolvable FullName (anonymous/unspeakable) reaches type-symbol resolution. Stale/incremental analysis that hasn't loaded all references.

Related errors

• Could not find type symbol for: {fullyQualifiedMetadataName}
• Could not find type symbol for: {fullyQualifiedMetadataName}
• Couldn't find method symbol for: {memberAccessSyntax}
• Couldn't get interceptable location for: '{node}'.
• Could not resolve type symbol for: {parameter.Type}

AI-assisted analysis of dotnet/efcore@dbf9771522 (2026-08-06). Data as JSON: /api/errors/a01cca4762068d85. Report an issue: GitHub.