dotnet/aspnetcore · error · InvalidOperationException

requires a non-null value for the parameter .

Error message

{nameof(DynamicComponent)} requires a non-null value for the parameter {nameof(Type)}.

What it means

DynamicComponent requires a non-null Type parameter naming the component to render. Omitting it leaves the component with nothing to render, which is rejected with InvalidOperationException.

Solutions

Always supply a non-null Type attribute.
Guard the DynamicComponent with @if(type is not null) so it only renders when a type is available.
Provide a fallback/default component type.

Example fix

// before
<DynamicComponent Type="@maybeNullType" />
// after
@if(maybeNullType is not null)
{
    <DynamicComponent Type="@maybeNullType" />
}

Defensive patterns

Strategy: validation

Validate before calling

// Guard DynamicComponent so it only renders with a non-null Type.
@if (componentType is not null)
{
    <DynamicComponent Type="@componentType" />
}

Prevention

Always supply Type, or guard the markup with @if(type is not null).
Provide a default/fallback component type when the dynamic type is unknown.
Avoid binding Type to expressions that can evaluate to null.

When it happens

Trigger: <DynamicComponent /> or <DynamicComponent Parameters="@p" /> without a Type, or Type bound to a variable that is null at render time.

Common situations: Type bound to a runtime-resolved value that is initially null, conditional Type that evaluates to null, or forgetting the attribute.

Related errors

AI-assisted analysis of dotnet/aspnetcore@3600ca084e (2026-08-11). Data as JSON: /api/errors/7b275ea4c39c85dc. Report an issue: GitHub.

Appendix: source

Thrown at src/Components/Components/src/DynamicComponent.cs:86

        {
            if (entry.Name.Equals(nameof(Type), StringComparison.OrdinalIgnoreCase))
            {
                Type = (Type)entry.Value;
            }
            else if (entry.Name.Equals(nameof(Parameters), StringComparison.OrdinalIgnoreCase))
            {
                Parameters = (IDictionary<string, object>)entry.Value;
            }
            else
            {
                throw new InvalidOperationException(
                    $"{nameof(DynamicComponent)} does not accept a parameter with the name '{entry.Name}'. To pass parameters to the dynamically-rendered component, use the '{nameof(Parameters)}' parameter.");
            }
        }

        if (Type is null)
        {
            throw new InvalidOperationException($"{nameof(DynamicComponent)} requires a non-null value for the parameter {nameof(Type)}.");
        }

        _renderHandle.Render(_cachedRenderFragment);
        return Task.CompletedTask;
    }

    void Render(RenderTreeBuilder builder)
    {
        builder.OpenComponent(0, Type);

        if (Parameters != null)
        {
            foreach (var entry in Parameters)
            {
                builder.AddComponentParameter(1, entry.Key, entry.Value);
            }
        }

View on GitHub (pinned to 3600ca084e)