Existing machine catalogs cannot be accessed for updates, and new catalogs cannot be created. 

Error code 500 logged on IIS server – sub-code not known
Exception: 
Citrix.Console.Models.Exceptions.ScriptException An error occurred while preparing the image. 
at Citrix.Console.PowerShellSdk.ProvisioningSchemeService.BackgroundTasks.ProvisioningSchemeTask.WaitForProvisioningSchemeActionCompletion(Guid taskId, Action`1 actionResultsObtained) 
at Citrix.Console.PowerShellSdk.ProvisioningSchemeService.BackgroundTasks.ProvisioningSchemeCreationTask.StartProvisioningAction() 
at Citrix.Console.PowerShellSdk.ProvisioningSchemeService.BackgroundTasks.ProvisioningSchemeCreationTask.RunTask() 
at Citrix.Console.PowerShellSdk.BackgroundTaskService.BackgroundTask.Task.Run() 

DesktopStudio_ErrorId : UnknownError 
ErrorCategory : NotSpecified 
ErrorID : FailedToCreateImagePreparationVm 
TaskErrorInformation : Terminated 
InternalErrorMessage : Unable to upload disk","" 

Contact the hypervisor vendor to correct the failure.

Problem Cause

Failure associated with hypervisor infrastructure can lead to this error.