dotnet/aspnetcore · error · InvalidOperationException

The property ' ' on component type ' ' cannot be set using…

Error message

The property '{parameterName}' on component type '{targetType.FullName}' cannot be set using a cascading value.

What it means

ThrowForSettingParameterWithCascadingValue is the inverse of 291: the framework attempted to deliver a cascading value to a property annotated with [Parameter] (ParameterAttribute) that does not accept cascading parameters (no CascadingParameterAttributeBase). Regular [Parameter] properties only receive explicitly-supplied values; routing a cascade into them is a type-of-binding mismatch.

Solutions

If the property should receive a cascading value, replace [Parameter] with [CascadingParameter] (and a matching Name if needed).
If the property should remain a direct parameter, supply the value explicitly rather than via CascadingValue.
Audit the property's attributes: a property should not be marked [Parameter] if it is meant to consume cascading values.

Example fix

// before
// Theme intended as cascading, but marked [Parameter]
[Parameter] public string? Theme { get; set; }

// after
[CascadingParameter] public string? Theme { get; set; }

Defensive patterns

Strategy: validation

Validate before calling

// Ensure a property meant to consume cascading values is annotated accordingly.
var prop = typeof(MyComponent).GetProperty("Theme");
bool acceptsCascade = prop?.GetCustomAttributes()
    .OfType<CascadingParameterAttributeBase>().Any() == true;
if (!acceptsCascade)
    throw new InvalidOperationException("Theme cannot accept a cascading value; mark [CascadingParameter].");

Prevention

Use [CascadingParameter] for properties that consume cascading values.
Reserve [Parameter] for explicitly-supplied values.
Review attribute usage whenever changing a property's data source.

When it happens

Trigger: Internally, when the cascading-value dispatch tries to write to a [Parameter]-only property. A custom renderer or test harness that pushes a cascading value at a property marked [Parameter]. Misconfiguration where a property intended to be cascading is annotated only with [Parameter].

Common situations: Annotating a property with [Parameter] when it should have been [CascadingParameter], then expecting a CascadingValue to populate it. Test infrastructure that drives cascading values into normal parameters. Component libraries where the attribute was applied incorrectly.

Related errors

AI-assisted analysis of dotnet/aspnetcore@3600ca084e (2026-08-11). Data as JSON: /api/errors/7b85d9b0b79307e0. Report an issue: GitHub.

Appendix: source

Thrown at src/Components/Components/src/Reflection/ComponentProperties.cs:232

        {
            throw new InvalidOperationException(
                $"Object of type '{targetType.FullName}' does not have a property " +
                $"matching the name '{parameterName}'.");
        }
    }

    [DoesNotReturn]
    private static void ThrowForSettingCascadingParameterWithNonCascadingValue(Type targetType, string parameterName)
    {
        throw new InvalidOperationException(
            $"The property '{parameterName}' on component type '{targetType.FullName}' cannot be set " +
            $"explicitly because it only accepts cascading values.");
    }

    [DoesNotReturn]
    private static void ThrowForSettingParameterWithCascadingValue(Type targetType, string parameterName)
    {
        throw new InvalidOperationException(
            $"The property '{parameterName}' on component type '{targetType.FullName}' cannot be set " +
            $"using a cascading value.");
    }

    [DoesNotReturn]
    private static void ThrowForCaptureUnmatchedValuesConflict(Type targetType, string parameterName, Dictionary<string, object> unmatched)
    {
        throw new InvalidOperationException(
            $"The property '{parameterName}' on component type '{targetType.FullName}' cannot be set explicitly " +
            $"when also used to capture unmatched values. Unmatched values:" + Environment.NewLine +
            string.Join(Environment.NewLine, unmatched.Keys));
    }

    [DoesNotReturn]
    private static void ThrowForMultipleCaptureUnmatchedValuesParameters([DynamicallyAccessedMembers(Component)] Type targetType)
    {
        var propertyNames = new List<string>();
        foreach (var property in targetType.GetProperties(BindablePropertyFlags))

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