Failed to start docker.service: Unit is masked.

The error message "Failed to start docker.service: Unit is masked" typically indicates that the Docker service has been marked as masked, which means it is disabled and cannot be started. This can happen if there are issues with the Docker installation or if it has been intentionally masked by the system administrator.

To resolve this issue, you can try the following steps:

1. Unmask the Docker service: Run the following command to unmask the Docker service.

   sudo systemctl unmask docker.service

2. Start the Docker service: Once the Docker service is unmasked, you can start it using the following command.

   sudo systemctl start docker.service

3. Verify the status: After starting the Docker service, you can check its status to ensure it is running without any errors.

   sudo systemctl status docker.service

If the issue persists or if you do not have administrative privileges to perform these actions, you may need to contact your system administrator for further assistance.