Roslyn doesn't work

[iMobCoding]

Type: Bug

Latest version of C# extension that works for me is 2.93.22. Then both 2.100.5 and 2.100.11 doesn't anymore. Everything is stuck and the output shows:

2025-11-19 10:39:36.862 [info] Installing C# dependencies...
2025-11-19 10:39:36.863 [info] 

2025-11-19 10:39:36.863 [info] Platform: win32, x86_64

2025-11-19 10:39:36.863 [info] 

2025-11-19 10:39:36.863 [info] Downloading package 'Language server for Roslyn Copilot integration' 

...and nothing is downloaded

Extension version: 2.100.11
VS Code version: Code 1.106.1 (cb1933bbc38d329b3595673a600fab5c7368f0a7, 2025-11-16T10:20:23.745Z)
OS version: Windows_NT x64 10.0.19045
Modes:

System Info

Item	Value
CPUs	Intel(R) Core(TM) i7-9750H CPU @ 2.60GHz (12 x 2592)
GPU Status	2d_canvas: enabled direct_rendering_display_compositor: disabled_off_ok gpu_compositing: enabled multiple_raster_threads: enabled_on opengl: enabled_on rasterization: enabled raw_draw: disabled_off_ok skia_graphite: disabled_off trees_in_viz: disabled_off video_decode: enabled video_encode: enabled vulkan: disabled_off webgl: enabled webgl2: enabled webgpu: enabled webnn: disabled_off
Load (avg)	undefined
Memory (System)	15.88GB (5.71GB free)
Process Argv	--crash-reporter-id ce604c1d-93c4-4582-bb19-8b7c7597f7ac
Screen Reader	no
VM	67%

A/B Experiments

vsliv368:30146709
binariesv615:30325510
nativeloc1:31344060
dwcopilot:31170013
dwoutputs:31242946
copilot_t_ci:31333650
e5gg6876:31282496
pythonrdcb7:31342333
6518g693:31334701
aj953862:31281341
4f60g487:31327383
nes-set-on:31351930
6abeh943:31336334
editstats-enabled:31346257
aa_c:31379599
t123456:31413567
0574c672:31404437
cloudbuttont:31379625
todos-1:31405332
qwen_all_req:31402696
control_gpt5applypatchexclusively:31412085
3efgi100_wstrepl:31403338
trigger-command-fix:31379601
auto_model_enabled:31385282
use-responses-api:31390855
9i271672:31419540
je187915:31401257
v2prompt_9f72f763:31415580
ec5jj548:31418076
copilot-nes-oct-t:31418199
ff8f5884:31411053
ag96h918:31418917
c0683394:31419495

[iMobCoding]

Well, I reported that everything works with 2.93.22 but it doesn't anymore. I can't make it download Roslyn anymore on any C# version. Tried with different C# Dev Kit too but without the success.

Edit: Installing the VSCode v1.105.1 with C# 2.100.5 and C# Dev Kit 1.80.7 works, but it obviously isn't the solution

[dibarbet]

@iMobCoding I have heard similar reports - can you try downgrading vscode itself to 1.105? Think something in 1.106 broke this.

I believe this is a vscode side bug and will likely need help tracking this down since I cannot reproduce the issue on my end. I posted details in this comment on what we need.

microsoft/vscode-dotnettools#2516 (comment)

[iMobCoding]

@dibarbet Yes I downgraded VSCode and it works with 1.105. Please check my "Edit" in the message above

So, I will try the bisect tool, but as I never used it before please be kind to give me the step by step instructions. I saw your message on the dotnettools git with 3 steps but still now sure how that should work...

Should I first downgrade to 1.105 and then go with steps 1 & 2? If so, then at which moment should I install the C# and C# Devi Kit? I have to remind you that latest C# and C# Devi Kit extensions don't work with vscode 1.105 so at some time I should also try to update the extension...

Please walk me through the process so I can try to help. Thanks

[iMobCoding]

Ok here is the update. While waiting for your answer I started looking into the bisect and first thing I needed was npm to install it. And I didn't have it at all, because I am a pure c# developer for Unity and I never needed node.js or npm. So after installing the node.js I simply started the latest vscode with the latest C# and C# Dev Kit.

Guess what, everything works now :) The step:
Downloading package 'Language server for Roslyn Copilot integration'
just continued and installed it for the first time. So I suppose there is a hard dependency on the npm somewhere

[dibarbet]

Great that it is working now, but yeah definitely we shouldn't require node / npm installed. That could be a useful hint, so thank you for trying that out!