Failed to start daemon: pid file found, ensure docker is not running or delete /var/run/docker.pid

Failed to start daemon: pid file found

This error message usually occurs when trying to start the Docker daemon and it detects the existence of a pid file. The pid file is used to store the process ID of a running daemon. This error can be resolved by ensuring that Docker is not already running or by deleting the pid file.

Here are the steps to resolve the issue:

1. Check if Docker is already running by executing the following command:

   sudo service docker status

   If it shows that Docker is running, you will need to stop the service before starting it again.

2. To stop the Docker service, execute the command:

   sudo service docker stop

   This will stop the running Docker daemon.

3. Delete the pid file by executing the command:

   sudo rm /var/run/docker.pid

   This will remove the pid file that is causing the error.

4. Start the Docker daemon again by executing the command:

   sudo service docker start

   The Docker daemon should start without any issues now.

Here is an example of executing the mentioned steps in a terminal:

$ sudo service docker status
    Docker is running
  $ sudo service docker stop
    Stopping Docker: [OK]
  $ sudo rm /var/run/docker.pid
  $ sudo service docker start  
    Starting Docker: [OK]