Debugging Blazor WASM in VSCode Holds Debug Session and Ports Open

[caffeinerobot]

Describe the bug

Starting a debug session for Blazor WASM from within VSCode works fine the first time. Closing the debug session and trying to start another one causes the below error to pop up.

"It looks like a browser is already running from an old debug session. Please close it before trying to debug, otherwise VS Code may not be able to connect to it.
(Cancel / Debug Anyway)"

Trying to start from command line using "dotnet run" after this fails as the port is still in use. The only way to resolve the issue is to reboot or go hunting for the orphaned process and force kill it.

I have always had this problem with Blazor WASM apps for dotnet-sdk-5.0 and now have the same problem with a brand new app created using dotnet-sdk-6.0.

To Reproduce

• Install VSCode, dotnet-sdk-6.0 and Chromium on Linux Debian 10.
• Create a new blazorwasm app: "dotnet new blazorwasm --auth Individual -o dotnet6blazorwasm -ho"
• Open in VSCode
• Debug the Server project
• Stop debugging
• Start debugging again

Further technical details

• ASP.NET Core version: 6.0
• The IDE (VS / VS Code/ VS4Mac) you're running on, and its version: VSCode 1.62.2
• Include the output of dotnet --info:

dotnet --info Output

.NET SDK (reflecting any global.json):
Version: 6.0.100
Commit: 9e8b04bbff

Runtime Environment:
OS Name: debian
OS Version: 10
OS Platform: Linux
RID: debian.10-x64
Base Path: /usr/share/dotnet/sdk/6.0.100/

Host (useful for support):
Version: 6.0.0
Commit: 4822e3c3aa

.NET SDKs installed:
3.1.415 [/usr/share/dotnet/sdk]
5.0.403 [/usr/share/dotnet/sdk]
6.0.100 [/usr/share/dotnet/sdk]

.NET runtimes installed:
Microsoft.AspNetCore.App 3.1.21 [/usr/share/dotnet/shared/Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 5.0.12 [/usr/share/dotnet/shared/Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 6.0.0 [/usr/share/dotnet/shared/Microsoft.AspNetCore.App]
Microsoft.NETCore.App 3.1.21 [/usr/share/dotnet/shared/Microsoft.NETCore.App]
Microsoft.NETCore.App 5.0.12 [/usr/share/dotnet/shared/Microsoft.NETCore.App]
Microsoft.NETCore.App 6.0.0 [/usr/share/dotnet/shared/Microsoft.NETCore.App]

To install additional .NET runtimes or SDKs:
https://aka.ms/dotnet-download

[TanayParikh]

Bug confirmed. Either the WebAssembly dev server or the debug proxy (not sure which one yet) isn't relinquishing the port when debugging is stopped.

[TanayParikh]

@caffeinerobot @cyberyaga, are you experiencing this issue on Linux / MacOS exclusively? Is anyone experiencing this on Windows?

I believe I've isolated the issue to the following code block which is Unix specific:

https://github.com/dotnet/razor-tooling/blob/2f6964417154c4d3823b94b8d4b0e151ea67e83d/src/Razor/src/Microsoft.AspNetCore.Razor.VSCode/src/BlazorDebug/BlazorDebugConfigurationProvider.ts#L78-L84

[caffeinerobot]

I’m only experiencing this issue on Linux, have recreated the issue on Debian 10 and Ubuntu 20.04. I’ve tried but haven’t been able to recreate on Windows 10. Sorry I can’t test on MacOS as I don’t have the hardware to try it. Let me know if there’s anything I can test to help out.