The error message "Attempting deletion of stale pid file" is recorded when starting Hyper-Q
A previous instance of Hyper-Q was not shut down properly. For example, a system crash occurred. The process identification number (PID) of that process was still present when Hyper-Q was re-started. Hyper-Q's startup logic will determine that there is no live process using that identifier, and will remove the stale PID file.
No action is required. Hyper-Q removes the stale PID file and starts as it should.