SKE patchday Q1 2026 – Containerd v2 upgrade
We are introducing Flatcar OS versions with the new containerd 2.0 runtime in STACKIT Kubernetes Engine.
containerd 2.0 is a major milestone that improves performance and reduces technical debt. It removes support for some deprecated features, you can find detailed information here
To ensure a smooth transition, we have extended the support for OS versions with containerd 1.7.
There are currently two preview OS versions of flatcar available:
4459.2.1(containerd 2.0)4230.2.4(containerd 1.7)
Key Dates:
- From today onwards: Flatcar
4459.2.4is available for all SKE users. - Jan 14, 2026: Flatcar
4230.2.4becomes the supported OS version. - Feb 11, 2026: Flatcar
4459.2.x(containerd 2.0) becomes the supported OS version and Flatcar4230.2.4(containerd 1.7) will be deprecated. If you haveauto updatesenabled, your Kubernetes worker nodes will automatically update to this version - March 11, 2026: Flatcar
4459.2.xbecomes the supported version and all flatcar versions withcontainerd 1.7will be removed. The regular SKE patchday cycle continues. You can find all information regarding version updates in SKE here.
OS versions with containerd 1.7 will remain available until March 2026 for sufficient evaluation time.
What you need to do
Please test your SKE workload beforehand using Flatcar version 4459.2.x. Testing is highly recommended to ensure your container images and configurations are compatible with the new runtime.
If you encounter problems during the migration, please contact us directly via support.stackit.cloud.