Deployment never completes, and fails to terminate when stop requested

Occasionally deployments can get stuck, and there's nothing that can be done to stop them. The only known fix is restarting the server.

The logs display:

No logs found.

If a stop has been requested, the stop button will be greyed out and display: "Build is currently being stopped... If there is no response you may need to kill the build manually.".

No new deployment of the affected project can be done until the broken one has been cleared.