Mandatory Site upgrade on first DDC fails with error "XDDS:9984398A".

Exception:
    Citrix.Console.Common.CitrixAggregateException One or more parallel operations failed
       at Citrix.Console.Common.CitrixParallel.InternalForEach[TIn](IEnumerable`1 items, Action`1 operation, Int32 maxSimultaneous)
       at Citrix.Console.PowerShellSdk.SiteInformationService.SiteInformationService.Refresh()
       at Citrix.Console.DeliveryCenter.UI.ViewModel.DesktopStudioViewModel.LoadSiteState(IProgressReporter progressReporter)
       at Citrix.Console.Common.OperationTimer.TimeBlock(Action operation)
       at Citrix.Console.CommonControls.ProgressDisplay.GenericProgressOperationWithFeedBack.PerformOperationInternal()
       at Citrix.Console.CommonControls.ProgressDisplay.ProgressWindowOperation.PerformOperation()
       at Citrix.Console.CommonControls.ProgressDisplay.ProgressWindowViewModel.PerformAction(Action operationComplete)
   
    
Inner Exception:
    Citrix.Console.Models.Exceptions.ScriptException An unexpected error occurred.
       at Citrix.Console.PowerShellInteraction.CmdletExecutionMethods.CreateException[T](ICommonLog logger, ExecutionResults`1 results, ICmdletExecutionHost host)
       at Citrix.Console.PowerShellInteraction.CmdletExecutionMethods.Execute[T](ISdkCmdlet`1 sdkCmd, ICmdletExecutionHost host, Boolean allowFailover)
       at Citrix.Console.PowerShellSdk.LicensingService.Scripts.GetLicenseInformationScript.RunScript()
       at Citrix.Console.PowerShellInteraction.PowerShellScript`1.Run()
       at Citrix.Console.PowerShellSdk.SiteInformationService.SiteInformationService.GetLicenseAlert()
       at Citrix.Console.PowerShellSdk.SiteInformationService.SiteInformationService.<>c__DisplayClass33_0.<Refresh>b__7()
       at Citrix.Console.Common.CitrixParallel.<>c__DisplayClass4_1`1.<InternalForEach>b__0(Object arg)
 

As a workaround follow below steps:
-> Stop Citrix Telemetry service on all the Controllers
-> Proceed with performing upgrade of remaining controllers.
-> Once upgrade is completed on all the controllers studio should work fine without any issues.
-> Start Citrix Telemetry Service on all the controllers.

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Problem Cause

Citrix Telemetry Service was causing issues while executing GetLicenseInformationScript on remote controllers as part of post upgrade checks.

https://docs.citrix.com/en-us/xenapp-and-xendesktop/7-15-ltsr/whats-new/known-issues.html