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

[ihorlazarenko]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

When InteractiveAuto render mode is used without prerendering, server rending is not started and Blazor hangs until wasm dlls are loaded.

Expected Behavior

When Blazor webassembly cache is empty server rendering should start no matter whether prerender is enabled or not.

Steps To Reproduce

1. Create Blazor project with Auto interactive render mode from template(interactive location per component).
2. Change render mode in Counter.razor to @rendermode @(new InteractiveAutoRenderMode(prerender:false))
3. build run
4. Change network latency in browser developer mode to Slow 3G or smth slow and clear Blazor cache dlls
5. Open Counter page and see that page is empty and Blazor does not use server rendering and only load dlls
   

Exceptions (if any)

No response

.NET Version

8.0.203

Anything else?

No response

[chadwickposey]

In OP description, they mention "When InteractiveAuto render mode is used without prerendering, server rending is not started and Blazor hangs until wasm dlls are loaded." In our case, Blazor just hangs and never completes the load. It loads all the assemblies, but the page is never rendered. If you refresh the browser, then (because the wasm assemblies are already downloaded maybe?) it renders the page properly. We are using Microsoft.AspNetCore.Components.WebAssembly 8.0.1 on the client side and Microsoft.AspNetCore.Components.WebAssembly.Server 8.0.1 on the server side, and the same directive for the components: InteractiveAutoRenderMode(prerender:false)

[mcse3010]

Updated both client and server to 8.0.5, and the problem still persists.

[MackinnonBuck]

@ihorlazarenko and @mcse3010, could you please try using the latest .NET 8 SDK and see if the issue still repros? I attempted to repro this on SDK version 8.0.404, and the app worked as expected (using Blazor Server on the initial page load, even with prerendering disabled and 3G throttling enabled).

[mcse3010]

This does not appear to be fixed. The reproduction steps are as follows:

• Create a client+server blazor application
• Set the start page to something other than /
• In that page, set the render mode to InteractiveAuto(prerender: false)
• Start the application using VS 2022 Enterprise in Debug Mode
• Note that the page appears white at the end of the wasm download and does not forward to the application

if you then reload the page, every time you debug from then on, it will load first try (no white screen) until it is forced to download the WASM assemblies again. -- you can force this by changing the mode to WasmClientOnly and debugging, then changing it back to Auto and debugging -- then it will show the white screen again:

Server nuGet packages:

Client nuGet packages:

Server is set to startup

The page it starts is in the client, not the server

[MackinnonBuck]

@mcse3010, are you able to provide us with a minimal repro project, hosted on GitHub as a public repository? I'm not experiencing the problem even after following your repro steps.