Unable to launch browser

[ofrades]

I get this error when I try to launch debug from vscode with the new support for one-step debugging for Blazor #1885

Unable to launch browser: "Could not open wss://localhost:5001/_framework/debug/ws-proxy?browser=ws%3A%2F%2F127.0.0.1%3A53267%2Fdevtools%2Fbrowser%2F53f91446-8e68-4407-95d8-d9c70558ff11": timeout after 30000ms

If I delete everything from .vscode folder I get the same error. I have the the latest Nightly JavaScript Debugger and the latest C# Extension.

Environment information

VSCode version: 1.46.0-insider
C# Extension: 1.22.0
JavaScript Debugger (Nightly): v2020.5.2917

Dotnet Information

.NET SDK (reflecting any global.json): Version: 5.0.100-preview.4.20258.7 Commit: 65f0fc2cad

Runtime Environment:
OS Name: Mac OS X
OS Version: 10.15
OS Platform: Darwin
RID: osx.10.15-x64
Base Path: /usr/local/share/dotnet/sdk/5.0.100-preview.4.20258.7/

Host (useful for support):
Version: 5.0.0-preview.4.20251.6
Commit: 47ec733ba7

.NET SDKs installed:
5.0.100-preview.4.20258.7 [/usr/local/share/dotnet/sdk]

.NET runtimes installed:
Microsoft.AspNetCore.App 5.0.0-preview.4.20257.10 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
Microsoft.NETCore.App 5.0.0-preview.4.20251.6 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]

[gregg-miskelly]

CC @captainsafia

[captainsafia]

Let's see if we can figure this out, @ofrades.

Typically, the error that you received occurs if the Blazor dev server has not started by the time the browser is launched. This can occur for a few reasons:

• A build error in your application prevents it from running correctly
• The application you are debugging is a hosted app but your config is associated with a standalone app
• Your application has a complicated build setup and takes longer than 30 seconds to build and run

To help debug this, can you check if:

• dotnet run works on your application without failing
• What the contents of your launch.json are?

[ofrades]

Thank for the reply @captainsafia.

dotnet run works without errors.

I have tried several launch.json configuration. If I run F5 without one, select the Blazor WebAssembly Debug, vscode creates this one for me:

{
	// Use IntelliSense to learn about possible attributes.
	// Hover to view descriptions of existing attributes.
	// For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
	"version": "0.2.0",
	"configurations": [
		{
			"type": "blazorwasm",
			"name": "Launch and Debug Blazor WebAssembly Application",
			"request": "launch"
		}
	]
}

Another thing I just noticed is that if I am running the app with dotnet run and run the debug (which makes no sense) I get one error that might be useful:

It was not possible to find any compatible framework version
The framework 'Microsoft.AspNetCore.App', version '3.1.0' was not found.
  - The following frameworks were found:
      5.0.0-preview.4.20257.10 at [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]

You can resolve the problem by installing the specified framework and/or SDK.

I am using Blazor 3.2.0 by the way and the only sdk I have is 5.0.100-preview.4.20258.7

[captainsafia]

I am using Blazor 3.2.0 by the way and the only sdk I have is 5.0.100-preview.4.20258.7

The 3.1.3 SDK is required in order to run Blazor WASM applications. This is likely what is causing the failure in this case. Blazor WASM isn't bundled with 5-preview4.

[ofrades]

Yes, that's it! Thanks.

[mahfuzmr]

In my case, it was one package missing :Microsoft.AspNetCore.Components.WebAssembly.DevServer
Happy coding.