Buildkite jobs fail with exit code -1: the agent stopped heartbeating

TL;DR

Check the agent logs and host metrics for networking, CPU, memory, and I/O pressure around the time heartbeats stopped. On the Elastic CI Stack for AWS with spot instances, abrupt termination also marks agents lost; use the log collector script to gather evidence.

Steps

1. Check the agent logs and host metrics for networking, CPU, memory, and I/O pressure around the time heartbeats stopped. On the Elastic CI Stack for AWS with spot instances, abrupt termination also marks agents lost; use the log collector script to gather evidence. Also check the command step timeout: a job exceeding it can be killed ungracefully and surface as -1 depending on the cancel-signal-timeout.

When to use

You are seeing this: Also check the command step timeout: a job exceeding it can be killed ungracefully and surface as -1 depending on the cancel-signal-timeout. Use this skill when you run into "Buildkite jobs fail with exit code -1: the agent stopped heartbeating".

When not to use

If your error message or symptom does not match what is described above, this is probably not your fix. Search for your exact error text instead of forcing this one to fit.

Versions

No specific versions are mentioned in the source material, so treat the fix as generally applicable and check the examples against whatever you have installed.

Why this happens

The original report does not dig into a root cause. It documents the symptom and the fix that resolved it.

Edge cases

• Also check the command step timeout: a job exceeding it can be killed ungracefully and surface as -1 depending on the cancel-signal-timeout.

Source: Official Buildkite agent lifecycle docs: a -1 exit code means Buildkite lost contact with the agent. Agents send heartbeat updates after registering; if none arrive for three consecutive minutes, the agent is marked lost and gets no more jobs. Common causes are networking issues and CPU, memory, or I/O constraints on the agent host.

Verified resolution: Check the agent logs and host metrics for networking, CPU, memory, and I/O pressure around the time heartbeats stopped. On the Elastic CI Stack for AWS with spot instances, abrupt termination also marks agents lost; use the log collector script to gather evidence. Also check the command step timeout: a job exceeding it can be killed ungracefully and surface as -1 depending on the cancel-signal-timeout.

Source URL: https://github.com/buildkite/docs/blob/HEAD/pages/agent/lifecycle.md