dotnet/efcore · error · InvalidOperationException

Model building is not supported when publishing with…

Error message

Model building is not supported when publishing with NativeAOT. Use a compiled model.

What it means

The runtime DbFunction cannot resolve its return-type mapping on demand under NativeAOT because that requires the type-mapping source (dynamic code). The TypeMapping getter throws CoreStrings.NativeAotNoCompiledModel when RuntimeFeature.IsDynamicCodeSupported is false.

Solutions

Generate a compiled model via 'dotnet ef dbcontext optimize' so DbFunction type mappings are baked in.
Register the compiled model on DbContextOptions at startup.
Avoid accessing TypeMapping on RuntimeDbFunction in app code; it is runtime infrastructure.
Confirm the publish profile sets up the compiled model reference.

Example fix

// before
// AOT publish, no compiled model -> TypeMapping getter throws

// after
dotnet ef dbcontext optimize
// then in DbContext configuration:
options.UseModel(CompiledModels.MyContext.Instance);

Defensive patterns

Strategy: validation

Validate before calling

if (RuntimeFeature.IsDynamicCodeSupported)
{
    _ = dbFunction.TypeMapping;
}
else
{
    throw new InvalidOperationException(
        "Compiled model required for DbFunction type mapping under NativeAOT.");
}

Type guard

static bool CanResolveTypeMappingAtRuntime()
    => RuntimeFeature.IsDynamicCodeSupported;

Prevention

Generate and reference a compiled model for NativeAOT deployments.
Avoid reading TypeMapping on RuntimeDbFunction in app code.
Verify the compiled model is wired into DbContextOptions at startup.

When it happens

Trigger: Accessing RuntimeDbFunction.TypeMapping in a NativeAOT-published app without a compiled model, where the type mapping was not precomputed and stored in _typeMapping.

Common situations: Publishing with <PublishAot>true</PublishAot> and querying a DbFunction at runtime; compiled model not generated or not wired into DbContextOptions; relying on runtime type-mapping discovery in an AOT binary.

Related errors

AI-assisted analysis of dotnet/efcore@3a2006ef56 (2026-08-11). Data as JSON: /api/errors/d5743d645dab1d95. Report an issue: GitHub.

Appendix: source

Thrown at src/EFCore.Relational/Metadata/RuntimeDbFunction.cs:101

    /// <summary>
    ///     Gets the name of the function in the model.
    /// </summary>
    public virtual string ModelName { get; }

    /// <summary>
    ///     Gets or sets the type mapping for the function's return type.
    /// </summary>
    /// <returns>The type mapping.</returns>
    public virtual RelationalTypeMapping? TypeMapping
    {
        get => _isScalar
            ? NonCapturingLazyInitializer.EnsureInitialized(
                ref _typeMapping, this, static dbFunction =>
                {
                    if (!RuntimeFeature.IsDynamicCodeSupported)
                    {
                        throw new InvalidOperationException(CoreStrings.NativeAotNoCompiledModel);
                    }

                    var relationalTypeMappingSource =
                        (IRelationalTypeMappingSource)((IModel)dbFunction.Model).GetModelDependencies().TypeMappingSource;
                    return !string.IsNullOrEmpty(dbFunction._storeType)
                        ? relationalTypeMappingSource.FindMapping(dbFunction._returnType, dbFunction._storeType)!
                        : relationalTypeMappingSource.FindMapping(dbFunction._returnType, dbFunction.Model)!;
                })
            : _typeMapping;
        set => _typeMapping = value;
    }

    /// <summary>
    ///     Adds a parameter to the function.
    /// </summary>
    /// <param name="name">The parameter name.</param>
    /// <param name="clrType">The parameter type.</param>
    /// <param name="propagatesNullability">A value which indicates whether the parameter propagates nullability.</param>

View on GitHub (pinned to 3a2006ef56)