Extension install fails with 'Failed to fetch' in offline environment

[bbartels]

Installing the vscode-csharp extension on a win->linux remote ssh setup on the remote host fails on newer versions of vscode-csharp. The latest version I managed to get it working with is: 2.69.25. Anything afterwards i've been unable to install.

Environment data

VS Code version: 1.99.1
C# Extension version: 2.74.24

C# logs

2025-04-20 15:52:34.464 [error] [Network] #31: https://marketplace.visualstudio.com/_apis/public/gallery/extensionquery - error POST Failed to fetch
2025-04-20 15:52:34.467 [error] [Network] #32: https://marketplace.visualstudio.com/_apis/public/gallery/extensionquery - error POST Failed to fetch
2025-04-20 15:52:34.468 [error] [Window] Failed to fetch: Failed: Failed to fetch
    at uqe.F (vscode-file://vscode-app/c:/Program%20Files/Microsoft%20VS%20Code/resources/app/out/vs/workbench/workbench.desktop.main.js:1834:55392)
    at async uqe.D (vscode-file://vscode-app/c:/Program%20Files/Microsoft%20VS%20Code/resources/app/out/vs/workbench/workbench.desktop.main.js:1834:52126)
    at async uqe.z (vscode-file://vscode-app/c:/Program%20Files/Microsoft%20VS%20Code/resources/app/out/vs/workbench/workbench.desktop.main.js:1834:47845)
    at async uqe.getExtensions (vscode-file://vscode-app/c:/Program%20Files/Microsoft%20VS%20Code/resources/app/out/vs/workbench/workbench.desktop.main.js:1834:47011)
    at async ldt.rb (vscode-file://vscode-app/c:/Program%20Files/Microsoft%20VS%20Code/resources/app/out/vs/workbench/workbench.desktop.main.js:3239:32246)
    at async ldt.pb (vscode-file://vscode-app/c:/Program%20Files/Microsoft%20VS%20Code/resources/app/out/vs/workbench/workbench.desktop.main.js:3239:31888)
    at async ldt.ob (vscode-file://vscode-app/c:/Program%20Files/Microsoft%20VS%20Code/resources/app/out/vs/workbench/workbench.desktop.main.js:3239:31449)
    at async ldt.install (vscode-file://vscode-app/c:/Program%20Files/Microsoft%20VS%20Code/resources/app/out/vs/workbench/workbench.desktop.main.js:3239:28845)
    at async Promise.all (index 0)
    at async Object.e [as settled] (vscode-file://vscode-app/c:/Program%20Files/Microsoft%20VS%20Code/resources/app/out/vs/workbench/workbench.desktop.main.js:30:80153)

Steps to reproduce

1. Cut internet connection
2. Install vscode-csharp: 2.74.24
3. Observe it failing as it can't query out to the vscode marketplace

Expected behavior

Should install without errors

Actual behavior

Fails to install due to network connectivity

[JoeRobich]

@bbartels If you have the internet cut, how are you installing the C# extension?

[bbartels]

You can Install from VSIX in VScode

[JoeRobich]

The C# extension requires the .NET Install Tool extension. Are you also installing it manually?

[bbartels]

Yep, that was also installed manually!
Has anything particular changed between the two mentioned versions? Seems odd that it would just stop working, one version to another.

[JoeRobich]

@bbartels Can you share the C# logs from the Output Pane? I suspect the ones in the issue description are not our because we do not communicate with the marketplace.

Has anything particular changed between the two mentioned versions?

You can see the changelog from the associated release https://github.com/dotnet/vscode-csharp/releases/tag/v2.72.34