We are trying to upgrade the machine image we use for the Micrometer build from ubuntu-2404:2025.09.1 to ubuntu-2404:2026.02.2. However, the job fails to run with an error message like the following:
Job was rejected because resource class medium, image ubuntu-2404:2026.02.2 is not a valid resource class
We didn’t explicitly specify a resource class, but we have since tried specifying a variety of resource classes. All fail with a similar message. Is there some issue on the CircleCI side or with our configuration?
Hi @shakuzen
I just had the same experience. It appears that the image was renamed. Check the current list of available images on CircleCI Developer - Machine Imagesubuntu-2404 - CircleCI.
I had success with ubuntu-2404:2026.02.20
machine-agent version 1.0.121027-1c678a53 (image: “ubuntu-2404:2026.02.20”, public ip: “3.84.54.181”, provider: “EC2”)
task-agent version 1.0.315880-984b2a35
Downloading task-agent: success after 324.963071ms.
Hi, these image names were meant to be internal and weren’t intended to be used directly, they got picked up by our indexer when they shouldn’t have. They’re designed to be called via the docker-docker29 alias rather than by name. The image will still be able to be used directly using ubuntu-2404:2026.02.20 in the meantime. We’ve added a flag to prevent images like these from being indexed going forward unless they’re explicitly intended for direct use.
@ahmedwab
Thank you for clarifying about the new images!
ubuntu-2404:2026.02.20 is actually a very useful update, since it bumps Docker from 28.x to 29.x and it updates Ubuntu from 24.04.3 to 24.04.4 LTS.
Would it be possible to officially release this image, or perhaps an image with a 2026.03.1 (March) tag?
According to the CircleCI Linux VM images support policy - CircleCI Docs it says:
We always aim to release a version of this image every three months. Tags will be supported on all versions we support.
and the last image on the updated list CircleCI Developer - Machine Imagesubuntu-2404 - CircleCI is showing 2025.09.1 which is by now approximately 6 months old.
workflows:
version: 2
build_test_and_deploy:
jobs:
- build:
context: org-global
Hi @MikeMcC399,
The intention is to wait for the new 26.04 machine before making an official release. In the meantime, you can continue using ubuntu-2404:2026.02.20 directly as it’s still available.
To clarify my earlier comment: when I said “internal,” I meant the image was designed to be accessed via a different alias (docker-docker29) rather than by name directly, not that it was unavailable for use.
Appreciate your patience!
Hi @ahmedwab
Did I understand you correctly that there will be a new ubuntu-2404 release when Ubuntu 26.04 is available?
Does that mean you are also planning to release an ubuntu-26.04 image?
I’m seeing Ubuntu 26.04 LTS (Resolute Raccoon) planned for release on April 23, 2026 with a beta release on March 26, 2026.
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Yes, that’s the plan! The intention is to release both a new ubuntu-2404 image and a new ubuntu-2604 image once Ubuntu 26.04 is available.
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