How to fix Error response from daemon: You cannot attach to a stopped container in Docker

First, verify the container's current state to confirm it is stopped:

docker ps -a

Look for your container in the output. The STATUS column will show:
- "Exited (0)" - Process completed successfully
- "Exited (1)" or other non-zero - Process crashed or encountered error
- "Created" - Container was created but never started

Note the container name or ID for the following steps.

Start the stopped container first, then attach to it:

# Start the container
docker start <container_name_or_id>

# Now attach to the running container
docker attach <container_name_or_id>

Important: If the container exits immediately after starting, the main process is completing too quickly. See the next steps for solutions.

For containers that run interactive shells (like those started with docker run -it), combine start and attach with the -ai flags:

docker start -ai <container_name_or_id>

The flags mean:
- -a (attach) - Attach STDOUT/STDERR and forward signals
- -i (interactive) - Attach container's STDIN

This is equivalent to starting and then attaching, but ensures the interactive session works correctly.

If the container keeps stopping, check the logs to understand why:

# View container logs
docker logs <container_name_or_id>

# View more detailed container info
docker inspect <container_name_or_id> --format='{{.State.ExitCode}}'

Common exit codes:
- 0: Process completed successfully (normal exit)
- 1: General error
- 137: Killed by SIGKILL (often OOM killer)
- 139: Segmentation fault

If you want to run commands in a container rather than attach to its main process, use docker exec:

# First, start the container
docker start <container_name_or_id>

# Then exec into it with a shell
docker exec -it <container_name_or_id> /bin/bash

Unlike docker attach, docker exec runs a new process inside the container rather than connecting to the existing main process. This is often more useful for debugging.

To prevent containers from stopping immediately, ensure they have a long-running foreground process:

# Run with a process that stays alive
docker run -d --name my_container <image> tail -f /dev/null

# Or use sleep infinity
docker run -d --name my_container <image> sleep infinity

# Now attach works (though these processes have no interactive output)
docker attach my_container

For shell-based images, use the -it flags:

docker run -dit --name my_container ubuntu
docker attach my_container