Can't debug ASP.NET Core hosted Blazor WebAssembly app under windows authentication

[bryp]

Hi folks, I am unable to debug an ASP.NET Core hosted Blazor WebAssembly app. The server project uses windows authentication. Steps to reproduce are simple and listed below.

Create a new ASP.NET Core hosted Blazor WebAssembly app.

Enable Windows Authentication on the Server project.

Press F5 to debug. My web browser is set to Chrome. Receive the following error message.

About Visual Studio

Attached please find visualstudio-js-debugger.txt.
visualstudio-js-debugger.txt

[javiercn]

@bryp thanks for contacting us.

@captainsafia do you know what's going on here? (I believe i've seen this reported in the past). Feel free to close it if there is an existing issue for it or a known answer.

Thanks for contacting us.
We're moving this issue to the Next sprint planning milestone for future evaluation / consideration. We will evaluate the request when we are planning the work for the next milestone. To learn more about what to expect next and how this issue will be handled you can read more about our triage process here.

[bryp]

Next sprint planning? FWIW - this one is blocking Blazor Wasm adoption at my company. Hard to believe one can't be able to debug under windows authentication, can someone help me to figure out a work around?

[javiercn]

@bryp this is our standard process for dealing with issues.

I've dug out the issue tracking improvements for Blazor Webassembly debugging #22589, there's a more general issue #27301 and this is a known issue in 5.0

See here for details. The issue mentions a workaround, but I don't seem to be able to find it by skimming the docs.

I understand that this might not be what you want to hear, I can only suggest you switch to a different auth scheme (one of the ones we support out of the box) or replace/turn-off windows auth when you want to debug the application.

Also, as a side note, we don't recommend using Windows Auth with single page applications unless you take appropriate steps to further protect your app against CSRF attacks

[javiercn]

@captainsafia if you know a workaround for this, feel free to comment/point to the docs.

I'm closing this issue since it's a duplicate of #27301

[bryp]

@javiercn This is certainly disappointing. To be clear, you do support Windows Auth out of the box. You just don't support debugging Windows Auth out of the box for Wasm, which makes this issue all the more strange. Also, as a side note, CSRF attacks have nothing to do with Windows Auth so CSRF protection applies to all Auth schemes and of course is good practice.

[captainsafia]

To be clear, you do support Windows Auth out of the box. You just don't support debugging Windows Auth out of the box for Wasm, which makes this issue all the more strange

This is correct. The implementation for debugging .NET on WASM is a little bit different than .NET on the Server which is why this issue presents itself here.

@bryp If you're up for it, you can try manually launching the debug proxy to see if that resolves the issue. To do that, you will need to:

1. Find the location of the BrowserDebugHost.dll assembly in the Microsoft.AspNetCore.Components.WebAssembly.DevServer package.
2. Launch the debugging proxy using dotnet BrowserDebugHost.dll.
3. Copy the address the server from Replace batch files with KVM #2 is listening on.
4. Modify the launchSettings.json file of your and update the inspectUri to the following:

"inspectUri": "ws://127.0.0.1:{portNumberFromStep2}/ws-proxy?browser={browserInspectUri}"

5. Start debugging in VS/VS Code.