Handling a NotFound UI

The Router component in Blazor has two important RenderFragment parameters. The first one is called Found and the other one is called NotFound. You can notice their UI piece values in the App.razor component:

<Router AppAssembly="@typeof(App).Assembly" AdditionalAssemblies="new[] { typeof(Component1).Assembly }">    <Found Context="routeData">
...
    </Found>
    <NotFound>
        <PageTitle>Not found</PageTitle>
        <LayoutView Layout="@typeof(MainLayout)">
            <p role="alert">Sorry, there's nothing at this
              address.</p>
      ...