dotnet/aspnetcore · error · ArgumentException

The component '{nameof(CascadingValue<TValue>)}' does not ac

Error message

The component '{nameof(CascadingValue<TValue>)}' does not accept a parameter with the name '{parameter.Name}'.

What it means

Thrown by CascadingValue<TValue>.SetParametersAsync when it receives a parameter whose name is not one of Value, ChildContent, Name, or IsFixed. CascadingValue only accepts these four parameters; any other attribute in markup is rejected as an ArgumentException rather than silently ignored.

Source

Thrown at src/Components/Components/src/CascadingValue.cs:90

            else if (parameter.Name.Equals(nameof(ChildContent), StringComparison.OrdinalIgnoreCase))
            {
                ChildContent = (RenderFragment)parameter.Value;
            }
            else if (parameter.Name.Equals(nameof(Name), StringComparison.OrdinalIgnoreCase))
            {
                Name = (string)parameter.Value;
                if (string.IsNullOrEmpty(Name))
                {
                    throw new ArgumentException($"The parameter '{nameof(Name)}' for component '{nameof(CascadingValue<TValue>)}' does not allow null or empty values.");
                }
            }
            else if (parameter.Name.Equals(nameof(IsFixed), StringComparison.OrdinalIgnoreCase))
            {
                IsFixed = (bool)parameter.Value;
            }
            else
            {
                throw new ArgumentException($"The component '{nameof(CascadingValue<TValue>)}' does not accept a parameter with the name '{parameter.Name}'.");
            }
        }

        if (_hasSetParametersPreviously && IsFixed != previousFixed)
        {
            throw new InvalidOperationException($"The value of {nameof(IsFixed)} cannot be changed dynamically.");
        }

        _hasSetParametersPreviously = true;

        // It's OK for the value to be null, but some "Value" param must be supplied
        // because it serves no useful purpose to have a <CascadingValue> otherwise.
        if (!hasSuppliedValue)
        {
            throw new ArgumentException($"Missing required parameter '{nameof(Value)}' for component '{GetType().Name}'.");
        }

        // Rendering is most efficient when things are queued from rootmost to leafmost.

View on GitHub (pinned to 294cab2f9b)

Solutions

  1. Check the parameter name spelling — only Value, ChildContent, Name, IsFixed are valid.
  2. If you intended a typed cascading source with more options, use CascadingValueSource<T> registered in DI instead.

Example fix

// before
<CascadingValue ValueData="@_value">
    <Child />
</CascadingValue>

// after
<CascadingValue Value="@_value">
    <Child />
</CascadingValue>
Defensive patterns

Strategy: validation

Validate before calling

var allowed = new[] { "Value", "ChildContent", "Name", "IsFixed" };
foreach (var p in parameters)
    if (!allowed.Contains(p.Name))
        throw new ArgumentException($"Unknown CascadingValue parameter: {p.Name}");

Prevention

When it happens

Trigger: Passing an unrecognized parameter in markup like <CascadingValue SomeOtherProp="x">, or programmatically building a parameter dictionary with a wrong key. The rejection happens in the else branch at CascadingValue.cs:88-91.

Common situations: Typo in a parameter name (e.g., <CascadingValue Values=...> instead of Value); confusing CascadingValue with CascadingValueSource API; attempting to pass extra configuration.

Related errors

AI-assisted analysis of dotnet/aspnetcore@294cab2f9b (2026-08-06). Data as JSON: /api/errors/bd2e054d774129f2. Report an issue: GitHub.