Not working offline, rendering C# base extension usseless

[alex-jitbit]

Describe the bug.

C# extension does dot work offline and it is caused by this extension. I can't code on a plane. "Go to definition" not working, no intellisense, no tooltips - nothing.

C# extension output

2025-10-05 13:41:42.734 [info] Locating .NET runtime version 9.0.1
2025-10-05 13:41:42.858 [info] Did not find .NET 9.0.1 on path, falling back to acquire runtime via ms-dotnettools.vscode-dotnet-runtime

Status bar has red error message "Error acquiring .NET!"

Extensions host output

2025-10-05 13:52:14.027 [error] Error: No internet connection detected: Cannot install .NET
    at v.next (/Users/jazz/.vscode/extensions/vscode-dotnet-runtime-library/dist/Utils/WebRequestWorkerSingleton.js:116:42)
    at Generator.next (<anonymous>)

Why it can't use the .NET I already have and that I successfully used 10 minutes ago when I was still online?

Please attach log file(s) here if you have any.

(log included above)

Reproduction Steps

Disable wifi, try coding in c#

Expected Behavior

should work

Exceptions & Errors (if any)

No response

.NET Install Tool Version

2.3.7

Your operating system? Please provide more detail, such as the version and or distro above.

OSX / Darwin / Mac

VS Code Version

No response

[alex-jitbit]

Another example, this time a Windows machine. Why does it attempt the download, just to detect that it's already installed?

ms-dotnettools.csharp requested to download the .NET ASP.NET Runtime.
Downloading .NET version(s) 9.0.10~x64~aspnetcore ...... Done!
.NET 9.0.10~x64~aspnetcore executable path: c:\Users\jazz\AppData\Roaming\Code\User\globalStorage\ms-dotnettools.vscode-dotnet-runtime\.dotnet\9.0.10~x64~aspnetcore\dotnet.exe

ms-dotnettools.csdevkit: Trying to install .NET 9.0.10~x64~aspnetcore but it already exists. No downloads or changes were made.

[nagilson]

This is an update service which is meant to keep you secure and provide improvements to the .net runtime. When you were on the plane, It should work offline if you had any .NET 9 version that was greater than the minimum version required to run the language server host, which would be 9.0.1, but it didn't find that on your machine. You may have gotten a C# extension update which went from requiring 8.0 or 9.0.0 to 9.0.1. 9.0.0 had some issues.

It may make you happy to hear we are deferring the download to happen in the background in the next version, though.