ubuntu-latest: builds hanging in 20251014.76 runner image

[iamtesch]

Description

We have a C++ project which the GitHub Action runner compiles. Normally, this builds fine (and continues to the next step in our workflow). After the latest ubuntu-24.04 image update, the CI build step running the compilation is hanging.

The failed build eventually times out, reporting

The hosted runner lost communication with the server. Anything in your workflow that terminates the runner process, starves it for CPU/Memory, or blocks its network access can cause this error.

We retried the builds with similar effect.

We have verified that the code is unchanged from the working build on the previous runner image.

Platforms affected

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

Runner images affected

• Ubuntu 22.04
• Ubuntu 24.04
• macOS 13
• macOS 13 Arm64
• macOS 14
• macOS 14 Arm64
• macOS 15
• macOS 15 Arm64
• macOS 26 Arm64
• Windows Server 2019
• Windows Server 2022
• Windows Server 2025

Image version and build link

https://github.com/actions/runner-images/releases/tag/ubuntu24%2F20251014.76

Is it regression?

Yes, this worked 3 days ago on image https://github.com/actions/runner-images/releases/tag/ubuntu24%2F20250929.60

Expected behavior

We expect the build to finish and continue to the next step in our workflow.

Actual behavior

The CI build step running the compilation is hanging when using the most recent ubuntu-latest image.

The failed build eventually times out, reporting

The hosted runner lost communication with the server. Anything in your workflow that terminates the runner process, starves it for CPU/Memory, or blocks its network access can cause this error.

Repro steps

Unfortunately, this is not on a public code repro, but we can reproduce by running the workflow which compiles the code.

[StephenSorriaux]

I am also having an issue with the latest 20251014.76 ubuntu image on a completely different kind of project (Ansible lib). In my case, some containers seem to not be running properly with this new image, while 20250929.60.1 was perfectly fine.

Job OK with 20250929.60.1: https://github.com/StephenSorriaux/ansible-kafka-admin/actions/runs/18549160071/job/52873181153
Exact same job (retry) but KO with 20251014.76.1: https://github.com/StephenSorriaux/ansible-kafka-admin/actions/runs/18549160071/job/53085265933

Downgrading from ubuntu-latest to ubuntu-22.04 (version 20251014.106.1) appears to solve the issue in my case.

[erik-bershel]

Hey @iamtesch!

The error indicates that the runner's resources have been exhausted. That is, some process has overloaded the available computing resources. To understand what's going on, I need minimal reprosteps or logs of the last successful and first failed builds. Without additional information, it will be difficult to continue the investigation, and therefore we will be forced to reject your request.

[iamtesch]

@erik-bershel thanks for looking into this!

Unfortunately I am not sure how to provide minimal repro steps given this occurs on a private repo. I am happy to send you logs directly or links to the individual builds if there is a way to do that privately?

[erik-bershel]

We don't have private communication channels unfortunately. 😞 I can offer several options:

• Contact GitHub support
• Remove secrets / sensitive information from the logs if any and forward them openly
• Wait for this week's release or this issue: 6.14.0-1012-azure kernel has broken IPv6 fragmentation (upgrade to 6.14.0-1014-azure is required) #13190

Considering that you're experiencing overload or connection loss, the issue could be related to kernel changes, although it's unlikely. 🤔

[iamtesch]

I'll sanitize the logs real quick and upload those. I'm assuming I should rerun with debug logs enabled?

[erik-bershel]

I'll sanitize the logs real quick and upload those. I'm assuming I should rerun with debug logs enabled?

We may start with what you have now. We'll ask for additional debug steps if required.