When working with Docker, you may encounter this common error:
Error response from daemon: Conflict. The container name "/your-container-name" is already in use by container
This typically happens when you try to run a new container using a name that’s already assigned to an existing (or stopped) container.
In this blog post, you’ll learn:
- Why this error occurs
- How to find and remove the conflicting container
- How to avoid the issue in future
❓ Why This Error Happens
Docker requires container names to be unique. When you try to start a container with a name that already exists (even for a stopped container), you’ll get the error:
docker run --name myapp myimage
🔴 Output:
docker: Error response from daemon: Conflict. The container name "/myapp" is already in use by container ...
This means there’s already a container named myapp, possibly created earlier and not removed.
✅ Solution 1: Remove the Old Container
First, check if the container exists—even in a stopped state:
docker ps -a
If you find the container with the same name, remove it:
docker rm myapp
Then, retry your docker run command.
✅ Solution 2: Rename the Old Container
If you want to keep the old container but avoid the name conflict, rename it:
docker rename myapp myapp_old
Now you’re free to use myapp again for a new container.
✅ Solution 3: Use a Different Name
Alternatively, assign a new name to the container:
docker run --name myapp_v2 myimage
This avoids touching existing containers.
🧼 Pro Tip: Clean Up Automatically
To ensure containers don’t linger around unintentionally, use the --rm flag:
docker run --rm --name myapp myimage
This removes the container once it exits, freeing up the name automatically.
🔍 Summary
| Task | Command |
|---|---|
| List all containers | docker ps -a |
| Remove a stopped container | docker rm <name> |
| Rename a container | docker rename old new |
| Use different container name | docker run --name newname |
| Auto-remove container on exit | docker run --rm |
📝 Conclusion
The error “Name is already in use by container” is Docker’s way of preventing name collisions. By removing or renaming old containers—or using unique names—you can easily avoid this issue.