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Docker Engine v29 — Compatibility Notice for Harness CI

Docker Engine v29 introduces significant API changes that are not backward-compatible with older Docker clients or tooling. These changes can impact CI pipelines running on:

  • Harness VM Runner
  • Harness Local Runner
  • Docker-in-Docker (DinD) workflows

This page summarizes the impact and required actions to ensure your pipelines continue to run successfully.

What Changed in Docker Engine v29​

Docker 29 introduces foundational API updates and removes support for older API versions. As a result:

  • Older Docker clients (for example, clients using API v1.24 or lower) cannot communicate with a Docker 29 daemon.
  • Several operations may fail with errors such as:
    • client is too old
    • Error response from daemon: unsupported API version
    • Error response from daemon: client version 1.xx is too old.
    • Minimum supported API version is 1.44. Please upgrade your client.

These errors typically occur when the Docker daemon upgrades but the Docker client or embedded tooling cannot negotiate the newer API version.

Official Documentation​

Impact on Harness CI VM Runner​

Docker 29 is not compatible with the Moby client bundled with the Harness CI VM Runner.
If a VM Runner environment upgrades to Docker 29, Docker-related steps may begin to fail.

Required Action​

  • If you install Docker manually (for example through user-data scripts), pin Docker CE to version 28.x or earlier.
  • Harness’s default VM Runner installation already pins Docker CE to 28.x to avoid compatibility issues.
  • Upgrade your VM Runner to the following version, which contains safe defaults:

drone-runners/drone-runner-aws: v1.0.0-rc.221

Impact on Harness CI Local Runner​

If your build VM automatically updates packages, it may pull Docker 29, which is incompatible with the Docker client bundled with the Local Runner.

Required Action​

  • If your Docker version is 29.x or higher, downgrade back to 28.x.
  • Pin the Docker package to prevent future auto-upgrades until a fully compatible version of the Local Runner is available.

Reference issue for similar API mismatch:

  • “client version 1.24 is too old” — traefik/traefik Issue #12253

Docker-in-Docker (DinD) Compatibility Guidelines​

If your CI pipeline uses Docker-in-Docker, you must prevent your DinD container from upgrading to Docker 29.

Required Actions​

  1. Pin your DinD image to a supported version such as:

    docker:24-dind

or any stable version in the 24.x series.

  1. Ensure the Docker client and daemon versions match (for example both using 24.x).

  2. Avoid unpinned tags, including:

    docker:dind docker:latest