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Docker: No space left on device

Recently I tried to spin up a new container and Docker refused with this error:

OSError: [Errno 28] No space left on device:

Not the most helpful message, but the root cause was simple: the disk used by the Docker engine was full.

As you can see in the screenshot below, I was eating up almost the full 250GB available for Docker:

Where did my disk space go?

Before deleting anything, let's find out what is actually using the space. Docker has a built-in command for this:

docker system df


This gives you a summary of the space used by images, containers, local volumes and build cache. Want more detail per item? Add the verbose flag:

docker system df -v

In my case, the usual suspects were to blame: old images, stopped containers and build cache that had been piling up for months.

Cleaning up

Start with the safest options and work your way up.

  • Remove all stopped containers:

docker container prune

  • Remove dangling images (untagged layers that are no longer referenced):

docker image prune

  • Remove all images not used by at least one container:

docker image prune -a

  • Remove the build cache:

docker builder prune

  • Or do everything in one go:

docker system prune -a

Remark: docker system prune does not touch volumes by default. That is on purpose, as volumes usually contain data you want to keep. You can add --volumes or run docker volume prune, but double-check what's inside first. Deleted volume data is gone.

Remark: docker image prune -a also removes images you might need again tomorrow. The next docker pull or docker build will take longer, but nothing is lost.

Trying again

After the cleanup I ran docker system df again to confirm the space was reclaimed, and started my containers again:

docker compose up

This time it started without complaints. Problem solved!

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