Blazor WebAssembly dotnet watch run --pathbase=/ doesn't work in .NET 8

[MaciekWin3]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

Hi, after the latest update to .NET 8, I discovered that the --pathbase flag is not working as it should. In the previous version, the app was served from the specified path, but in the new version, it is being ignored. I am using this option to debug my Blazor Extension in Azure DevOps as I need to specify a different path than the default one. The command I am using is:

dotnet watch run --pathbase=/dist

Then the app is served from /dist folder, and I can access my app and debug easily using hot reloading. At the root level, I get this message: "The server is configured only to handle request URIs within the PathBase '/dist'." On .NET 8, this flag is simply ignored, and the app is served from the default path.

Expected Behavior

I expected the app to run from specified path with the dotnet watch run --pathbase=path command after updating to .NET 8, like it did before. But now, the flag isn't working, and the app runs from the default path instead.

Steps To Reproduce

To reproduce the issue, launch a Blazor WebAssembly project using the command dotnet watch run --pathbase=/dist and observe whether the application is served at the specified path ('/dist' in this case).

Exceptions (if any)

No response

.NET Version

8.0.100

Anything else?

No response

[mkArtakMSFT]

@tmat is this something you've potentially changed? I don't recall us making any changes in this area during .NET 8.

[afouadr]

Working:
dotnet run --pathbase=path

Not working:
dotnet watch --pathbase=path
dotnet watch run --pathbase=path

[ghost]

To learn more about what this message means, what to expect next, and how this issue will be handled you can read our Triage Process document.
We're moving this issue to the .NET 9 Planning milestone for future evaluation / consideration. Because it's not immediately obvious what is causing this behavior, we would like to keep this around to collect more feedback, which can later help us determine how to handle this. We will re-evaluate this issue, during our next planning meeting(s).
If we later determine, that the issue has no community involvement, or it's very rare and low-impact issue, we will close it - so that the team can focus on more important and high impact work.

[tmat]

Hot Reload is disabled when running the above command line with SDK 7:

>dotnet watch --verbose run --pathbase=/dist
dotnet watch ⌚ Did not find a HotReloadProfile or running a non-default command. Watching with legacy behavior.

We no longer disable it with SDK 8.

A workaround is to explicitly disable Hot Reload --no-hot-reload like so:

dotnet watch run --no-hot-reload --pathbase=/dist

[KenDRhyD]

I ran into this recently. I have .Net 7 Blazor app that is working on my MacOS system (via VSCode), and I attempted to update to .Net 8 by installing the 8.0.2 SDK and then changing the csproj file to update the framework and WebAssembly versions, and I was getting the same error message.

So I deleted the bin and obj folders completely and tried again and found that a "dotnet run" allows the "https://localhost:7035/" URL to invoke my code, but a "dotnet watch" reports the "The server is configured only to handle request URIs within the PathBase '/SMaLL'." error! And is I append "/SMaLL" to the URL then all resources report 404 error!

At least I can use the run command, but it is a pain to have to kill and restart with each code change, as I was able to use watch before.