How to fix Error response from daemon: pull access denied for myimage, repository does not exist or may require 'docker login' in Docker

First, confirm that the image name is spelled correctly and exists on Docker Hub or your target registry.

# Search for the image on Docker Hub
docker search nginx

# Check available tags at hub.docker.com or use the API
# For example, visit: https://hub.docker.com/_/nginx/tags

Common naming mistakes:
- mongodb should be mongo
- ngnix should be nginx
- postgress should be postgres

If using a specific tag, verify the tag exists on the registry.

If the repository requires authentication, log in before pulling:

# Log in to Docker Hub
docker login

# Or log in to a private registry
docker login registry.example.com

Important: If you use sudo for Docker commands, you must also use sudo when logging in:

sudo docker login
sudo docker pull myimage:tag

Your credentials are stored in ~/.docker/config.json (or /root/.docker/config.json when using sudo).

Always use the complete image path including the registry and namespace:

# Instead of just the image name
docker pull myimage

# Use the full path
docker pull docker.io/myusername/myimage:tag

# For private registries, include the registry URL
docker pull registry.example.com/myproject/myimage:tag

For Docker Hub official images, the namespace is library:

docker pull docker.io/library/nginx:latest

If your docker-compose.yml references images that should be built locally, build them first:

# Build all images defined in docker-compose.yml
docker-compose build

# Or build a specific service
docker-compose build myservice

# Then start the services
docker-compose up

Check your docker-compose.yml for any image: references that point to local images rather than remote ones. These need a corresponding build: section or must be built separately.

Docker Hub has rate limits for image pulls:
- Anonymous users: 100 pulls per 6 hours
- Authenticated free users: 200 pulls per 6 hours
- Paid subscriptions: Higher limits

To check your current rate limit status:

# Get an auth token and check limits
TOKEN=$(curl -s "https://auth.docker.io/token?service=registry.docker.io&scope=repository:library/alpine:pull" | jq -r .token)
curl -sI -H "Authorization: Bearer $TOKEN" https://registry-1.docker.io/v2/library/alpine/manifests/latest | grep -i ratelimit

If rate limited, either:
1. Wait for the limit to reset (6 hours)
2. Log in to Docker Hub to get higher limits
3. Use a Docker Hub mirror or cache

If you're still having issues after logging in, try resetting your Docker credentials:

# Log out from Docker Hub
docker logout

# Or log out from a specific registry
docker logout registry.example.com

# Remove the credentials file (backup first if needed)
mv ~/.docker/config.json ~/.docker/config.json.backup

# Log in again
docker login

This clears any corrupted or outdated credentials that might be causing authentication failures.