Error boundaries may block redirects by handling exceptions of type `NavigationException`

[meisam-dehghan]

When you try to navigate to another page by using the NavigationManager.NavigateTo in a blazor web app introduced in .net8,the following exception is thrown :
Microsoft.AspNetCore.Components.NavigationException: 'Exception of type 'Microsoft.AspNetCore.Components.NavigationException' was thrown.'
Even if you put the logic in a try/catch block,the exception would be still thrown and the page would stay on the current route.This means that if,for example,you wanted to create a login page that should take the user to the main page after a successful login form submission,the user would still stay on the login page!

Even though the issue had previously been brought up by @danroth27 at #49143 and closed as done later on,the problem still persists in the final version of .net8.I've also created a sample project that you can check out in the following repo:
Blazor Web App With Custom Cookie-based Authentication

[javiercn]

@meisam-dehghan thanks for contacting us.

Is there any functional impact to your app? Do you actually get redirected to the error page or similar?

This is an exception that is thrown and caught internally by the framework, and as such, you only get to see it if you are debugging and have enabled breaking on caught exceptions.

If this is the case, can you please create a minimal repro project that demonstrates the issue as a public GitHub repository we can take a look at?

Hi @meisam-dehghan. We have added the "Needs: Author Feedback" label to this issue, which indicates that we have an open question for you before we can take further action. This issue will be closed automatically in 7 days if we do not hear back from you by then - please feel free to re-open it if you come back to this issue after that time.

[meisam-dehghan]

@javiercn

Is there any functional impact to your app? Do you actually get redirected to the error page or similar?

Yeah, The app cant redirect to the main page after a successful login. It simply stays there. The main page will be shown with logout button only after I refresh the page manually! What's more, I'm not redirected to the error page, the page just hangs in there.

This is an exception that is thrown and caught internally by the framework, and as such, you only get to see it if you are debugging and have enabled breaking on caught exceptions.

Actually, I tried running the app without debugging as well, but the problem still persists.
Here's the public repo you can clone and try for yourself:
Blazor Web App With Custom Cookie-based Authentication

[rob-king-volpara]

I'm seeing this too. I have a Blazor SSR app and using the EditForm component.

@inject NavigationManager _navigationManager
<EditForm EditContext="editContext" OnValidSubmit="SignIn" FormName="LoginForm" Enhance>
....
</EditForm>

Nothing fancy about the form, it's just two bound fields to a model using the EditContext as per the example on the MS docs.

public void SignIn()
{
    _navigationManager.NavigateTo($"api/authentication/login?tenant={Model.Customer}&email={Model.Email}&returnUrl={ReturnUrl}", true);
}

When hitting the SignIn() method, an exception is thrown and no navigation occurs.

Unhandled exception rendering component: Exception of type 'Microsoft.AspNetCore.Components.NavigationException' was thrown.
      Microsoft.AspNetCore.Components.NavigationException: Exception of type 'Microsoft.AspNetCore.Components.NavigationException' was thrown.
         at Microsoft.AspNetCore.Components.Endpoints.HttpNavigationManager.NavigateToCore(String uri, Boolean forceLoad)
         at Volpara.Components.Pages.Welcome.SignIn() in C:\...\Components\Pages\Welcome.razor:line 124
         at Microsoft.AspNetCore.Components.EventCallbackWorkItem.InvokeAsync[T](MulticastDelegate delegate, T arg)
         at Microsoft.AspNetCore.Components.ComponentBase.Microsoft.AspNetCore.Components.IHandleEvent.HandleEventAsync(EventCallbackWorkItem callback, Object arg)
         at Microsoft.AspNetCore.Components.EventCallback`1.InvokeAsync(TValue arg)
         at Microsoft.AspNetCore.Components.Forms.EditForm.HandleSubmitAsync()
         at Microsoft.AspNetCore.Components.ComponentBase.CallStateHasChangedOnAsyncCompletion(Task task)
         at Microsoft.AspNetCore.Components.RenderTree.Renderer.GetErrorHandledTask(Task taskToHandle, ComponentState owningComponentState)

Interestingly, it doesn't seem to even need to be on a form post. For instance, I have this OnInitialized() method which throws an exception if it falls into the _navigationManager case:

protected override void OnInitialized()
{
    Model ??= new();
    editContext = new(Model);
    editContext.OnValidationRequested += CheckForm;
    messageStore = new(editContext);

    if (TenantRoute.HasValue())
    {
        CustomerInfo customer = _customerInfoService.GetCustomerInfo(TenantRoute);
        if (customer != null)
        {
            Model.Customer = TenantRoute;
        }
        else
        {
            _navigationManager.NavigateTo($"/");
        }
    }
}

I'm using SDK 8.0.101

[rob-king-volpara]

My current workaround is to disable enhanced forms and directly embed the script:

@if (string.IsNullOrEmpty(_redirectTo))
{
    <EditForm EditContext="_editContext" OnValidSubmit="SignIn" FormName="LoginForm">
....
    </EditForm>
}
else
{
    <script>
        window.location = "@_redirectTo";
    </script>
}

[vulcandragi]

I'm receiving the same error, the only way I found to solve it is with the render mode server active.

[MackinnonBuck]

@meisam-dehghan, when a component is rendered using static server rendering, NavigationManager.NavigateTo() will always throw an exception. This is by design. The exception is meant to be caught by the framework so it can be handled as a redirect.

In the repro you provided, there is a try/catch around NavigationManager.NavigateTo(), so the exception never bubbles up to be handled as a redirect. If you remove the try/catch, then the app works correctly.

If you want to have a try/catch around the code with the NavigateTo() call and catch all exceptions except NavigationException, you could use a filtered exception handler:

try
{
    // ...
    NavigationManager.NavigateTo(...);
    // ...
}
catch (Exception ex) when (ex is not NavigationException)
{
    // ...
}

However, if the NavigationException bubbles up but does not get correctly caught by the framework, that might be a framework bug. This seems like what might be happening in @rob-king-volpara's case.

@rob-king-volpara, would you be able to provide a minimal repro that demonstrates the problem you're experiencing, so that we can investigate the issue further?