Setting rendermode to InteractiveAuto does not use Interactive Server rendering

[pushmlk]

Is there an existing issue for this?

• I have searched the existing issues

This issue is similar to another github issue that was closed without a resolution (link)

Describe the bug

This issue has two parts:

1. When InteractiveAuto render mode is used with prerendering, the page first renders with Static Server rendering and then, as soon as the WASM is loaded, it switches to Interactive WebAssembly rendering.
   It does not switch to Interactive Server rendering while the WASM is loading.
   This results in a degraded user experience as, after the page loads, it is not interactive for a few seconds until the WASM is loaded.
   I'm displaying @RendererInfo.Name on the page to determine which renderer is being used.

2. When InteractiveAuto render mode is used without prerendering, the page takes a few seconds to load, and
   loads with Interactive WebAssembly rendering.

In both cases, It looks like the page never switches to Interactive Server rendering.

In case this helps - when a page with InteractiveAuto render mode is loaded on FireFox with WASM support turned off, the page loads with Static Server rendering and does not switch to Interactive Server rendering.

Expected Behavior

1. When InteractiveAuto render mode is used with prerendering, the page should:
   1. first render with Static Server rendering, and then
   2. quickly switch to Interactive Server rendering (and become interactive), and the finally
   3. switch to Interactive WebAssembly rendering after the WASM is loaded.
2. When InteractiveAuto render mode is used without prerendering, the page should:
   1. load with Interactive Server rendering (and become interactive), and then
   2. switch to Interactive WebAssembly rendering after the WASM is loaded.

Steps To Reproduce

I uploaded a solution to highlight this issue (here).
The issue can be seen in the counter.razor page.

1. Run the solution in debug mode. Refresh the counter page several times. You will see the render mode go from Static directly to WebAssembly (Issue#1).
2. Change the render mode on the top of the page to @rendermode @(new InteractiveAutoRenderMode(prerender: false)) and run the solution in debug mode.
   Refresh the counter page several times. You will see the render mode go directly to WebAssembly without first going to Server Interactive rendering (Issue#2).

Exceptions (if any)

No response

.NET Version

10.0

Anything else?

I tested this with .NET 10.0 and Visual Studio Community 2022 (64-bit) - Preview (version 17.14.13) in debug mode;
The issue also exists in .NET 8.0 and 9.0

[MihuBot]

I'm a bot. Here is a possible related and/or duplicate issue (I may be wrong):

• InteractiveAutoRenderMode(prerender:false)) does not use interactive server rendering #54657

[javiercn]

@pushmlk thanks for contacting us.

If you navigate with inprivate mode, do you also observe the same behavior?

[pushmlk]

@pushmlk thanks for contacting us.

If you navigate with inprivate mode, do you also observe the same behavior?

Yes, it's the same behavior in an InPrivate Microsoft Edge browser window.

[javiercn]

@pushmlk are you testing this locally or in a remote server.

[pushmlk]

@pushmlk are you testing this locally or in a remote server.

I'm testing locally on a laptop with Windows 11 Pro.

[javiercn]

@pushmlk works fine for me

A few things to note, as I think there is a mismatch in expectations here.

• If Blazor detects webassembly is already cached, it will start webassembly directly and won't start server.
• If an auto component is already executing on a render mode (server or wasm), all other auto components will follow the same until a full-page refresh happens.

To force rendering on server for testing purposes, clear the application cache.