How to fix Error response from daemon: invalid reference format in Docker

# Wrong
docker pull MyApp:latest
docker run MyImage

# Correct
docker pull myapp:latest
docker run myimage

# Wrong - breaks if path contains spaces
docker run -v $(pwd):/app myimage

# Correct - handles spaces in paths
docker run -v "$(pwd)":/app myimage

# Also correct - use full quoting
docker run -v "$(pwd):/app" myimage

# Check if variable is set
echo $IMAGE_TAG

# This will fail if IMAGE_TAG is empty
docker pull myrepo/myimage:$IMAGE_TAG

# Use default value as fallback
docker pull myrepo/myimage:${IMAGE_TAG:-latest}

# Or verify before running
if [ -z "$IMAGE_TAG" ]; then
  echo "IMAGE_TAG is not set"
  exit 1
fi

# If you copied a command, try retyping it manually
# Pay special attention to:
# - Hyphens (-)
# - Colons (:)
# - Slashes (/)

# Use hexdump to detect hidden characters
echo "your-command" | hexdump -C

# Wrong formats
docker pull ubuntu:          # Trailing colon
docker pull ubuntu:18.04:2   # Multiple colons
docker pull ubuntu-          # Trailing hyphen

# Correct formats
docker pull ubuntu           # Uses :latest implicitly
docker pull ubuntu:22.04     # Explicit tag
docker pull myregistry.com/myimage:v1.0.0

# Wrong - -d flag after image name
docker run nginx -d

# Correct - flags before image name
docker run -d nginx

# Wrong - -p flag in wrong position
docker run myimage -p 8080:80

# Correct
docker run -p 8080:80 myimage

# Check line endings
file yourscript.sh

# Convert CRLF to LF using sed
sed -i 's/\r$//' yourscript.sh

# Or use dos2unix
dos2unix yourscript.sh