[Bug] Windows setup occasionally failing

[tothambrus11]

• I have gone through the action README, documentation and wiki.
• I don't see my issue listed in existing issues.

Describe the bug
Flaking setup on Windows. Very rarely, the setup on Windows is failing. It cannot be reproduced consistently. Any idea what's the issue? Is swift.org reporting wrong data?

Logs

Run SwiftyLab/setup-swift@latest
  with:
    swift-version: 6.2
    development: false
    check-latest: false
    dry-run: false
    cache-snapshot: true
    prefer-oss-toolchain: false
    prefer-visual-studio-linker: false
    update-sdk-modules: false
  env:
    swift-version: 6.2
Syncing swift.org data
  "C:\Program Files\Git\bin\git.exe" init D:\a\_actions\SwiftyLab\setup-swift\latest\swiftorg
  Initialized empty Git repository in D:/a/_actions/SwiftyLab/setup-swift/latest/swiftorg/.git/
  "C:\Program Files\Git\bin\git.exe" fetch https://github.com/apple/swift-org-website.git bdb912136b36ac6123c36512f4f3b40bd25de914 --depth=1 --no-tags
  From https://github.com/apple/swift-org-website
   * branch            bdb912136b36ac6123c36512f4f3b40bd25de914 -> FETCH_HEAD
  "C:\Program Files\Git\bin\git.exe" checkout FETCH_HEAD --detach
  HEAD is now at bdb9121 [Windows] Add Nightly swift-6.3-DEVELOPMENT-SNAPSHOT-2026-05-05-a
Detecting current platform
  Detected windows platform with arch "x64"
Installing Swift toolchain snapshot swift-6.2.4-RELEASE
  No SDKs to install

See full workflow run: https://github.com/hylo-lang/hylo-language-server/actions/runs/25496834597/job/74818730335
Runner:

• Name: windows-2025
• OS: Windows
• Version: whatever is in windows-2025

[soumyamahunt]

Hey @tothambrus11 , Thanks for reporting this. Are you still seeing this failure? I have seen this kind of failure twice in my CI in two consecutive days around 1 week before and now it seems to be fixed.

I am guessing the error could be due to some npm setup issues with Github hosted runners which now seems to be fixed. Let me know if you are still

[tothambrus11]

Hi! We saw this happening 3 days ago last time: https://github.com/hylo-lang/hylo/actions/runs/26049745538/job/76629249486

Also, once or twice several months earlier. It's almost always not reproducible, but last time it only worked for the second retry.

Do you know what the diagnostic "no SDKs to install" diagnostic is triggered by? Is it related to some network request failing?

[soumyamahunt]

Do you know what the diagnostic "no SDKs to install" diagnostic is triggered by? Is it related to some network request failing?

This is an info diagnostics I log. This action started supporting Swift SDK installation while back:

- uses: SwiftyLab/setup-swift@latest
  with:
    sdks: static-linux;wasm;android

I log this if no SDKs are passed. You should get the same log in case of success as well.

The crash seems to be happening with nodejs, similar issue found: nodejs/node#62260.
@tothambrus11 can you try the existing workaround actions/runner#4447 (comment), see if this fixes the issue permanetly:

Setting machine level env ACTIONS_RUNNER_DISABLE_NODE_MAGLEV=1 or step level env ACTIONS_RUNNER_DISABLE_NODE_MAGLEV=1

[tothambrus11]

Thanks, I'll report in a month if we see this again. Maybe we could set this variable within the action, so that users get this behavior by default without having to modify their settings globally. Or if there is an issue within NodeJS, we should find a way to report it in a reproducible way to NodeJS.

[soumyamahunt]

@tothambrus11 I did some more digging into this and it seems the variable needs to be set before node loads this action. Hence it will not be possible for this action to set this environment variable.