GitHub Actions · Ubuntu 26.04 · Checked November 4, 2026

setup-swift on Ubuntu 26.04: Version "26.04" of Ubuntu is not supported

ubuntu-latest is moving from Ubuntu 24.04 to 26.04 between October 19 and November 19, 2026 (what else changes). swift-actions/setup-swift keeps a fixed list of Ubuntu versions, and 26.04 is not on it in v2.4.0, its latest release (November 2025). So the step fails before it downloads a toolchain, whatever swift-version you ask for.

What it looks like

Run swift-actions/setup-swift@v2
Error: Unexpected error, unable to continue. Please report at https://github.com/swift-actions/setup-swift/issues
Version "26.04" of Ubuntu is not supported
Stacktrace:
Error: Version "26.04" of Ubuntu is not supported
    at Object.getSystem (.../dist/index.js:436:15)

The list in v2.4.0 is latest, 24.04, 22.04 and 20.04, and its Swift versions end at 6.2.1. The issue has been open since September 18 (setup-swift #805), and the pull request that moves the action to a newer installer is not merged.

Only Swift 6.4 has a 26.04 build

swift.org publishes Ubuntu 26.04 toolchains from Swift 6.4.0 (September 14, 2026). Swift 6.3.3 and older have Ubuntu 22.04 and 24.04 builds only (the Swift install page), so a newer action does not help with an older version either. The 24.04 build of an older Swift can start on 26.04, but building with Foundation then looks for libxml2.so.2, and 26.04 has libxml2.so.16 ("cannot open shared object file" on Ubuntu 26.04).

Where the reports came from

A release-candidate check failed in its setup-swift step on the 26.04 image, and the fix pinned that job to ubuntu-24.04 (arrow-swift #199, #200).
A Swift 6.1 Linux test job stopped during toolchain setup on ubuntu-latest, before the build, and was pinned to ubuntu-24.04 (swift-sdk #320).

Fix for Swift 6.4: use the Swift on the image

Both the 24.04 and the 26.04 images already have Swift 6.4.1 (the image readmes). If your project builds with 6.4, drop the setup-swift step and print the version so the log shows it:

- run: swift --version
- run: swift build

When GitHub updates the image, the preinstalled Swift moves with it. If you need one exact version, use the container below.

Fix for an older Swift: run the job in the Swift container

jobs:
  test:
    runs-on: ubuntu-latest
    container: swift:6.2-noble
    steps:
      - uses: actions/checkout@v7
      - run: swift test

The official swift images have a tag for each version and Ubuntu release (6.1-noble, 6.2-noble, 6.3-noble, 6.4-resolute and so on), so the toolchain and its libraries come from the same Ubuntu whatever the runner image is.

Or pin the runner

runs-on: ubuntu-24.04 keeps setup-swift v2 working, as both projects above did, until GitHub retires that image.

Telling it apart

"is not supported" comes from the action before any download. "does not exist at URL" with ubuntu2604 in it means the installer reached swift.org and that version has no 26.04 build.
Look at "Set up job": the Runner Image group shows the image. Until November 19 a re-run can land on 24.04 and pass, so a green re-run proves nothing.

Other 26.04 failures

wg-quick "Permission denied" on Ubuntu 26.04: new AppArmor profiles let wg-quick and wg read configuration and key files only under /etc/wireguard/, so a wg0.conf in the workspace fails even with sudo.
"cannot open shared object file" on Ubuntu 26.04: libxml2 is libxml2.so.16 and ICU is 78, so a cache saved on 24.04, or a binary built for it, cannot find libxml2.so.2 or libicudata.so.74.
Docker-in-Docker on Ubuntu 26.04: the legacy iptables modules are not loaded, so a dockerd inside a container that uses iptables-legacy, such as the dev container docker-in-docker feature :2 or :3, fails with "can't initialize iptables table `nat'"; move the feature to :4 or load the modules on the runner.
pg_dump 18 on Ubuntu 26.04: PostgreSQL on the image and from apt is 18, so dumps start with SET transaction_timeout = 0 and a PostgreSQL 16 service rejects them with "unrecognized configuration parameter".
apt on Ubuntu 26.04: renamed and removed packages.
"coreutils: unknown program": most core tools are uutils.

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