Solve Docker error: “unable to delete (must be forced) – image is referenced in multiple repositories”

I’ve had to brush up my Docker skills again due to some side projects I’m working on. So I ran into some basic issues I wanted to elaborate on. In this blog post: “image is referenced in multiple repositories.”

I had to remove a Docker image from my machine using the rmi command.

docker rmi <image_id>

To my surprise, I was unable to delete the image. The following error was thrown:

Error response from daemon: conflict: unable to delete <image ID> (must be forced) - image is referenced in multiple repositories

For example, this can happen when you have an image that is referenced by multiple tags or multiple names. In the following example, I created two mirrors of redis.

docker pull redis:latest
docker tag redis:latest redis:my_new_tag
docker tag redis:latest redis_mirror:latest

The result is:

When you try to remove the image by ID, Docker does not know which image (mirror) you are referring to. There are two ways one can tackle this.

Instead of trying to remove the image using its image id, you’ll have to remove all repositories individually, by referencing them with their name and tag. The last one can be removed by referring to the image ID.

docker rmi redis:my_new_tag
rocker rmi redis_mirror
docker rmi 881

But there is also a faster solution. You can force docker to remove an image. By using the -f flag and the image’s (short or long) ID, the image gets untagged and is removed. Like this:

docker rmi -f <image ID>

And that’s how it’s done.