"setup-node" incorrectly downloads latest on "ubuntu-slim"

[mikeharder]

Description

On ubuntu-slim, using setup-node with a node-version of 24 or 24.x downloads 24.13.1, instead of using 24.13.0 from the cache. On ubuntu-latest, both 24 and 24.x use the cached version. On both images, leaving version empty "" used the cached 24.13.0.

Also reported at actions/setup-node#1492.

Platforms affected

• Azure DevOps
• GitHub Actions - Standard Runners
• GitHub Actions - Larger Runners

Runner images affected

• Ubuntu 22.04
• Ubuntu 24.04
• Ubuntu Slim
• macOS 14
• macOS 14 Arm64
• macOS 15
• macOS 15 Arm64
• macOS 26
• macOS 26 Arm64
• Windows Server 2022
• Windows Server 2025
• Windows Server 2025 with Visual Studio 2026

Image version and build link

VM Image
  - OS: Linux (x64)
  - Source: Docker
  - Name: ubuntu:24.04
  - Version: 20260120.46.1

Build showing behavior on ubuntu-slim and ubuntu-latest:

https://github.com/mikeharder/test-setup-node/actions/runs/21978003995

Is it regression?

unknown

Expected behavior

ubuntu-latest:

Run actions/setup-node@v6
  with:
    node-version: 24.x
    check-latest: false
    token: ***
    package-manager-cache: true
##[debug]isExplicit: 
##[debug]explicit? false
##[debug]isExplicit: 20.20.0
##[debug]explicit? true
##[debug]isExplicit: 22.22.0
##[debug]explicit? true
##[debug]isExplicit: 24.13.0
##[debug]explicit? true
##[debug]evaluating 3 versions
##[debug]matched: 24.13.0
##[debug]checking cache: /opt/hostedtoolcache/node/24.13.0/x64
##[debug]Found tool in cache node 24.13.0 x64
Found in cache @ /opt/hostedtoolcache/node/24.13.0/x64

Actual behavior

ubuntu-slim:

Run actions/setup-node@v6
  with:
    node-version: 24.x
    check-latest: false
    token: ***
    package-manager-cache: true
##[debug]isExplicit: 
##[debug]explicit? false
##[debug]evaluating 0 versions
##[debug]match not found
Attempting to download 24.x...
Acquiring 24.13.1 - x64 from https://github.com/actions/node-versions/releases/download/24.13.1-21889660756/node-24.13.1-linux-x64.tar.gz
Extracting ...
/usr/bin/tar xz --strip 1 --warning=no-unknown-keyword --overwrite -C /home/runner/work/_temp/59cebe8b-4470-41c9-973c-af5e8e15f687 -f /home/runner/work/_temp/693643e2-4471-4597-b383-bb315dcd6f5e
Adding to the cache ...

Repro steps

name: setup-node

on:
  pull_request:
  workflow_dispatch:

permissions:
  contents: read

jobs:
  test:
    runs-on: ${{ matrix.os }}

    strategy:
      matrix:
        node-version: ['24.x', '24', '']
        os: [ubuntu-slim, ubuntu-latest]

    steps:
      - uses: actions/setup-node@v6
        with:
          node-version: ${{ matrix.node-version }}
      
      - run: node -v

https://github.com/mikeharder/test-setup-node/blob/192c349bd754b02fcb70057fa5ebe9b6315c73a0/.github/workflows/setup-node.yaml

[GitPaulo]

Hey, ubuntu-slim currently includes a preinstalled Node, but it isn’t exposed.

As a workaround, omit node-version (or pass an empty string) to actions/setup-node use the preinstalled Node, or pin an exact version to control what’s installed. Team is working on the container to be more consistent with other ubuntu images.

[mikeharder]

Hey, ubuntu-slim currently includes a preinstalled Node, but it isn’t exposed.

As a workaround, omit node-version (or pass an empty string) to actions/setup-node use the preinstalled Node, or pin an exact version to control what’s installed. Team is working on the container to be more consistent with other ubuntu images.

The workaround is a bit tricky if you have shared code that calls setup-node and needs to run on both ubuntu-slim and ubuntu-latest. But we might be able to do something like this:

1. call node -v to check current version
2. if match the requested node-version (respecting wildcards), no-op
3. else, call setup-node with requested version