RequestId flashed across the page

[Varorbc]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

RequestId flashed across the page

Expected Behavior

No response

Steps To Reproduce

1. dotnet new blazor -ai
2. dotnet run
3. navigation to error page

Exceptions (if any)

No response

.NET Version

9.0.100-rc.1.24452.12

Anything else?

No response

[javiercn]

@Varorbc thanks for contacting us.

That's been the behavior since 8.0. What's happening is that the page becomes interactive and at that point the requestId is not available. The way to handle this is to check the metadata on the App.razor component and render it statically.

[javiercn]

Moving this to the backlog in case we decide to make improvements to the template.

[Varorbc]

That's been the behavior since 8.0.

@javiercn I noticed it works great on 8.0, but there's an issue only in 9.0

[Varorbc]

@javiercn I'm really curious why it's running twice. The first time it runs, Activity.Current is available, but the second time it's not, which causes the RequestId to show up and then disappear right away.

[javiercn]

This only happens when navigating to the page, not when an actual error is triggered.

When an error is triggered, we always render statically, but if you navigate and have global interactivity, then the page will first render, then interactivity will start and re-render (hence the flashing).

Couple of ways to deal with this:

• Using `[PersistentState] to just persist the original TraceId. It will get rid of the flashing.
• Use https://learn.microsoft.com/en-us/aspnet/core/blazor/components/render-modes?view=aspnetcore-9.0#static-ssr-pages-in-an-interactive-app on the template code.

Separately, we should consider updating the Error page to use the Activity associated with the component host (that would work for server/client/SSR)

[javiercn]

@Varorbc we merged a fix for this in 11.0.

Leveraging persistent component state should address this on your end. If you want to give it a try and let us know.

-    private string? RequestId { get; set; }
+    [PersistentState]
+    private string? RequestId { get; set; }

-    protected override void OnInitialized() =>
-        RequestId = Activity.Current?.Id ?? HttpContext?.TraceIdentifier;
+    protected override void OnInitialized()
+    {
+        RequestId ??= Activity.Current?.Id ?? HttpContext?.TraceIdentifier;
+    }

[Varorbc]

@javiercn I tried your suggestion, but I ran into a new exception:

InvalidOperationException: A public property 'RequestId' on component type 'BlazorApp1.Components.Pages.Error' with a public getter wasn't found.

This happens because properties marked with [PersistentState] must be public, while in the current code it is private.

Another issue I noticed is that the component still executes twice. The reason the RequestId doesn’t disappear is only because of the ??= operator, which prevents it from being overwritten on the second execution.

[ilonatommy]

@Varorbc, I think we have a misunderstanding about the "execution twice". It is by design and it is not recognized as an issue. As mentioned above, when the component renders with interactive state, it is expected to retrigger OnInitialized. The issue here is how the project is set up to adapt to this behavior and making sure that this behavior happens across all versions after the "rehydration" mechanism was introduced.