# Docker "failed to set up container networking" - Fix Net Setup

> Fix Docker "failed to set up container networking" in CI - iptables/bridge problems, exhausted address pools, or nested-container networking limits.

Source: https://latchkey.dev/learn/docker/docker-failed-to-set-up-container-networking  
Updated: 2026-06-25

Docker could not wire up networking for the container - typically an iptables/bridge issue on the runner, or it ran out of address space to allocate a subnet.

## Diagnose it: read the container, not the compose file

A container that exits immediately in CI has almost always logged the reason and then been cleaned up. Capture the logs and the exit code before changing configuration.

```Terminal
# why did it stop?
docker ps -a --format '{{.Names}}\t{{.Status}}\t{{.Image}}'
docker logs <container> 2>&1 | tail -50
docker inspect <container> --format '{{.State.ExitCode}} {{.State.OOMKilled}} {{.State.Error}}'
```

> `OOMKilled: true` means the kernel killed it for memory, and no amount of application debugging will explain the log. Exit code 137 is the same event seen from outside.

## FAQ

### What causes Docker "failed to set up container networking"?

There are 3 common causes: iptables/bridge misconfigured on the runner, address pool exhausted, and docker-in-docker / nested networking limits. Docker programs iptables rules for container connectivity.

### How do I fix Docker "failed to set up container networking"?

There are 2 fixes depending on which cause you have: reclaim networks and address space and fix the runner’s networking prerequisites. Work through them in order, since the first is the most common.

### What does Docker "failed to set up container networking" actually mean?

A docker run or docker compose up fails with failed to set up container networking, often citing iptables, the bridge, or address-pool exhaustion.

### How do I stop Docker "failed to set up container networking" happening again?

Prune unused networks regularly on long-lived runners. The prevention section lists 3 changes that keep it from recurring.

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Latchkey runs CI/CD that repairs its own failures. Agent entry points: https://latchkey.dev/agent.txt, https://latchkey.dev/openapi.json, https://latchkey.dev/llms.txt