dotnet/aspnetcore · error · InvalidOperationException

The RouteView component requires a non-null value for the pa

Error message

The RouteView component requires a non-null value for the parameter RouteData.

What it means

Thrown in RouteView.SetParametersAsync. RouteView is the component that renders the matched page inside its layout; it requires RouteData (the matched page type + route values). If the parameter is still null after SetParameterProperties, RouteView cannot know which page to render and aborts.

Source

Thrown at src/Components/Components/src/RouteView.cs:60

    /// and accept a parameter named <see cref="LayoutComponentBase.Body"/>.
    /// </summary>
    [Parameter]
    public Type DefaultLayout { get; set; }

    /// <inheritdoc />
    public void Attach(RenderHandle renderHandle)
    {
        _renderHandle = renderHandle;
    }

    /// <inheritdoc />
    public Task SetParametersAsync(ParameterView parameters)
    {
        parameters.SetParameterProperties(this);

        if (RouteData == null)
        {
            throw new InvalidOperationException($"The {nameof(RouteView)} component requires a non-null value for the parameter {nameof(RouteData)}.");
        }

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

    /// <summary>
    /// Renders the component.
    /// </summary>
    /// <param name="builder">The <see cref="RenderTreeBuilder"/>.</param>
    [UnconditionalSuppressMessage("Trimming", "IL2110", Justification = "Layout components are preserved because the LayoutAttribute constructor parameter is correctly annotated.")]
    [UnconditionalSuppressMessage("Trimming", "IL2111", Justification = "Layout components are preserved because the LayoutAttribute constructor parameter is correctly annotated.")]
    [UnconditionalSuppressMessage("Trimming", "IL2118", Justification = "Layout components are preserved because the LayoutAttribute constructor parameter is correctly annotated.")]
    protected virtual void Render(RenderTreeBuilder builder)
    {
        var pageLayoutType = _layoutAttributeCache
            .GetOrAdd(RouteData.PageType, static type => type.GetCustomAttribute<LayoutAttribute>()?.LayoutType)
            ?? DefaultLayout;

View on GitHub (pinned to 294cab2f9b)

Solutions

1. Always pass RouteData to RouteView in the Found template: <Found>...<RouteView RouteData="@routeData" DefaultLayout="@typeof(MainLayout)"/>...</Found>.
2. If using RouteView directly, ensure a non-null RouteData is constructed and bound.
3. Confirm the enclosing Router actually invokes Found with a valid RouteData.

Example fix

<!-- before -->
<Found Context="routeData">
    <RouteView DefaultLayout="@typeof(MainLayout)" />
</Found>

<!-- after -->
<Found Context="routeData">
    <RouteView RouteData="@routeData" DefaultLayout="@typeof(MainLayout)" />
</Found>

// In the Router Found template, always forward RouteData to RouteView.
<Found Context="routeData">
    @if (routeData is null) throw new InvalidOperationException("Router supplied null RouteData");
    <RouteView RouteData="@routeData" DefaultLayout="@typeof(MainLayout)" />
</Found>

When it happens

Trigger: Rendering <RouteView> without a RouteData parameter, or passing RouteData="@null". Typically RouteView is rendered from a Router's Found template as <RouteView RouteData="@routeData" ...>; omitting RouteData or a Router that never supplies it triggers this.

Common situations: A custom Router Found template that renders <RouteView> but forgets to forward RouteData; using RouteView standalone without wiring it to a Router; a refactor that renamed/removed the RouteData binding.

Related errors

• The value must implement IComponent.
• The Router component requires a value for the parameter AppA
• The Router component requires a value for the parameter Foun
• The following routes are ambiguous: '{existingText}' in '{ex
• Setting NotFound and NotFoundPage properties simultaneously

AI-assisted analysis of dotnet/aspnetcore@294cab2f9b (2026-08-06). Data as JSON: /api/errors/56b4025bd5616ca8. Report an issue: GitHub.