XS71ECU1016 fails with automated update

Attempts to apply this hotfix using XenCenter fail with the error shown in the text below and in the attached image. Seems to be the case on all XS 7.X installations.
Note: "cannot read input as a ZipFile" seems to be the clue here...

2018-05-12 11:45:49,358 ERROR XenAdmin.Actions.DownloadAndUnzipXenServerPatchAction [10] - Exception occurred when extracting downloaded archive: Cannot read input as a ZipFile
Parameter name: zipStream
2018-05-12 11:45:49,358 ERROR XenAdmin.Actions.AsyncAction [10] - System.Exception: Cannot extract the update file from downloaded archive. Please see application logs for more details.
   at XenAdmin.Actions.DownloadAndUnzipXenServerPatchAction.ExtractFile()
   at XenAdmin.Actions.DownloadAndUnzipXenServerPatchAction.Run()
   at XenAdmin.Actions.AsyncAction.RunWorkerThread(Object o)
2018-05-12 11:45:49,374 ERROR XenAdmin.Actions.AsyncAction [10] -    at XenAdmin.Actions.DownloadAndUnzipXenServerPatchAction.ExtractFile()
   at XenAdmin.Actions.DownloadAndUnzipXenServerPatchAction.Run()
   at XenAdmin.Actions.AsyncAction.RunWorkerThread(Object o)
2018-05-12 11:45:49,374 WARN  Audit [10] - Operation failure: DownloadAndUnzipXenServerPatchAction: Connection unknown: Extracting update XS71ECU1016
2018-05-12 11:45:49,409 ERROR XenAdmin.Wizards.PatchingWizard.PatchingWizard_AutomatedUpdatesPage [10] - Failed to carry out plan.
System.Exception: Cannot extract the update file from downloaded archive. Please see application logs for more details.