Quick Summary
The 'DOCKER_FAILED_TO_START' error indicates that the Docker service was unable to initialize and begin running correctly. This can prevent you from starting Docker containers or managing existing ones.
Common Causes
- Port conflicts: Another application might be using the ports that Docker needs (e.g., port 2375, 2376). This prevents Docker from binding to those ports.
- Corrupted Docker installation: Files related to the Docker installation may be damaged or incomplete, leading to startup failures.
- Insufficient system resources: Docker might require more memory, CPU, or disk space than is currently available on the system.
- Firewall restrictions: Firewall rules may be blocking Docker from communicating with the network or other containers.
- Incorrect Docker configuration: Settings in the Docker configuration files (e.g., `daemon.json`) could be invalid or conflicting.
- Kernel incompatibility or missing features: The Linux kernel may be too old, missing required features (like cgroups or namespaces), or the Linux kernel modules are missing.
Step-by-Step Fixes
Method 1: Check and Resolve Port Conflicts
Step 1: Identify conflicting processes. Use the command netstat -tulnp (Linux) or netstat -ano | findstr ":2375" (Windows PowerShell) to find processes using Docker's ports (e.g., 2375, 2376).
Step 2: Stop the conflicting process. Use the appropriate command (e.g., kill on Linux or taskkill /PID on Windows) to stop the process.
Step 3: Reconfigure Docker (optional). If stopping the process isn't feasible, change Docker's ports in the daemon.json file (Linux: /etc/docker/daemon.json, Windows: C:\ProgramData\DockerDesktop\settings.json). Add or modify the 'hosts' key to specify different ports e.g., {"hosts": ["tcp://0.0.0.0:2377"] }. Restart Docker after modifying the configuration.
Method 2: Restart Docker Service
Step 1: Stop the Docker service. Depending on your operating system, use the appropriate command: sudo systemctl stop docker (Linux), or through the Services app (services.msc) on windows or using the Docker Desktop UI to stop the service.
Step 2: Start the Docker service. Similarly, use: sudo systemctl start docker (Linux), or using the Services app or CLI in case of desktop docker instance.
Step 3: Check Docker service status. Linux: sudo systemctl status docker. Windows: Docker Desktop UI or PowerShell using Get-Service docker.
Method 3: Reinstall Docker
Step 1: Uninstall Docker. Follow the official uninstallation instructions for your operating system (e.g., using package manager commands like apt remove docker-ce on Debian/Ubuntu, or the uninstaller on Windows).
Step 2: Remove Docker data directories. Delete the directories containing Docker's persistent data. These locations depends on the OS and the used docker software. These are often located in locations such as /var/lib/docker, /var/run/docker, and C:\ProgramData\DockerDesktop\. WARNING: This will erase your existing containers, images, and volumes.
Step 3: Reinstall Docker. Download and install the latest version of Docker from the official Docker website or using your OS appropriate package manager.
Method 4: Check System Resources
Step 1: Monitor CPU and Memory usage. Use tools like top or htop (Linux) or Task Manager (Windows) to monitor CPU and memory usage.
Step 2: Increase Resources (if necessary). If CPU or memory usage is consistently high, consider increasing system resources. This could involve adding more RAM, upgrading the CPU, or closing unnecessary applications.
Step 3: Adjust Docker's Resource Limits. You can configure resource limits for Docker containers in Docker Desktop by going to Settings -> Resources. You may also use the command line using the --cpus and --memory flags.
Method 5: Check Firewall Settings
Step 1: Verify Firewall Configuration. Review your firewall rules (e.g., using iptables on Linux or Windows Firewall) to ensure that Docker's traffic is not being blocked.
Step 2: Allow Docker Traffic. Create rules to allow Docker to communicate on necessary ports (e.g., 2375, 2376) and with other containers. Example iptables rule: sudo iptables -A INPUT -p tcp --dport 2375 -j ACCEPT.
Method 6: Review Docker Configuration Files
Step 1: Locate Docker configuration files. Common configuration files include daemon.json (Linux: /etc/docker/daemon.json, Windows: C:\ProgramData\DockerDesktop\settings.json) and Docker Compose files (docker-compose.yml).
Step 2: Validate configuration. Carefully review the contents of these files for syntax errors, invalid settings, or conflicting options. Use a JSON validator to check the daemon.json file. Ensure the YAML syntax is correct in Docker Compose files.
Step 3: Correct any errors. Fix any identified errors in the configuration files and restart the Docker service.