dotnet/aspnetcore · error · InvalidOperationException

The {nameof(RouteView)} component requires a non-null value

Error message

The {nameof(RouteView)} component requires a non-null value for the parameter {nameof(RouteData)}.

What it means

RouteView is the component that renders the matched page inside a Router; it reads its RouteData parameter and dispatches to the page component described there. A null RouteData is a configuration error: RouteView has nothing to render and cannot guess one, so SetParametersAsync throws InvalidOperationException before requesting a render. The contract is that the host (Router) always supplies RouteData.

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 3600ca084e)

Solutions

Confirm RouteView is always rendered with a non-null RouteData — typically <RouteView RouteData="@routeData" /> inside the Router's Found template.
If using RouteView standalone, pass a RouteData constructed from a known page type.
Audit the Found render fragment on the parent Router to ensure routeData (the lambda parameter) is forwarded, not shadowed.
Add a null check at the call site and fall back to a known route rather than letting RouteView receive null.

Example fix

// before (App.razor)
<Found Context="routeData">
    <RouteView />  <!-- RouteData omitted, throws -->
</Found>

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

Defensive patterns

Strategy: validation

Validate before calling

// Before rendering RouteView (e.g. in a custom host), confirm RouteData is non-null.
if (routeData is null)
    throw new InvalidOperationException("RouteData must be supplied to RouteView.");
builder.OpenComponent<RouteView>(0);
builder.AddAttribute(1, nameof(RouteView.RouteData), routeData);
builder.CloseComponent();

Type guard

static bool IsValidRouteData(RouteData? d) => d?.PageType is not null;

Prevention

Always forward the Found lambda's routeData parameter to <RouteView RouteData="@routeData" />.
When using RouteView standalone, construct a RouteData from a known page type before passing it.
Add a default value or guard in markup: @if (routeData is not null) { <RouteView RouteData=@routeData /> }.
Keep RouteView inside the Router's Found template.

When it happens

Trigger: Declaring <RouteView /> in markup without a RouteData parameter, or binding RouteData to an expression that evaluates to null. Also triggered by manually constructing a RouteView and calling SetParametersAsync with a ParameterView that omits RouteData.

Common situations: Removing the @bind or [Parameter] wiring for RouteData in a custom App.razor; a typo in the parameter name causing null binding; using RouteView outside a Router without supplying RouteData manually; reflection-based component activation that skips the parameter.

Related errors

AI-assisted analysis of dotnet/aspnetcore@3600ca084e (2026-08-11). Data as JSON: /api/errors/70a09a30a08812c9. Report an issue: GitHub.