Upgrade from StoreFront 2.1 to 2.5 fails.

Event log reported the following error:

CitrixStoreFront-x64.msi' failed with error code 1603. Fatal error during installation.

StoreFront log from the installation reported the following error:

Remove-DSFeatureInstance: Error Access to the path 'C:\inetpub\wwwroot\Citrix\Roaming' is denied.

StoreFront log Remove-DSFeatureInstance (All)_29-04-2014_09.39.27.log reported the following error:

Deleting folder on disk 'C:\inetpub\wwwroot\Citrix\Roaming'
Waiting 500 ms for folder "C:\inetpub\wwwroot\Citrix\Roaming" to disappear after being marked for deletion.
Waiting 500 ms for folder "C:\inetpub\wwwroot\Citrix\Roaming" to disappear after being marked for deletion.
The folder "C:\inetpub\wwwroot\Citrix\Roaming" has been marked for deletion but appears to still have handles locking it preventing its removal.
RecurseDelete folder removal complete for 'C:\inetpub\wwwroot\Citrix\Roaming'
RemoveFeatureFiles completed
RemoveTemplateFilesStep:Uninstall ends
Step: 1 is of type: Citrix.DeliveryServices.Framework.Web.Deployment.WebSteps.DestroyWebApplicationStep
DestroyWebApplicationStep starts
Destroying web app at SiteId: 1, VirtualPath /Citrix/Roaming
Step: 1 of type: Citrix.DeliveryServices.Framework.Web.Deployment.WebSteps.DestroyWebApplicationStep FAILED
System.UnauthorizedAccessException: Access to the path 'C:\inetpub\wwwroot\Citrix\Roaming' is denied.

In the installation log called Citrix-DeliveryServicesRoleManager-2014-04-29 11-37-37.log, the installation failed on DeliveryServicesRole:

[2014-04-29 11:40:36][1984][Verbose] Broadcasting Event: package_failed
Event Name: package_failed
Event Arguments:
Id : DeliveryServicesRole
Message : An error occurred while updating one of StoreFront's subcomponents.
Item : DeliveryServicesRole (Role)

In the installation log called CitrixMsi-CitrixStoreFront-x64-2014-04-29-11-38-36.log, a powershell action failed:

MSI (s) (60:D8) [11:39:26:183]: Invoking remote custom action. DLL: C:\Windows\Installer\MSIBE63.tmp, Entrypoint: RemoveConfiguredFeatures
SFXCA: Extracting custom action to temporary directory: C:\Windows\Installer\MSIBE63.tmp-\
SFXCA: Binding to CLR version v4.0.30319
Calling custom action Citrix.DeliveryServices.InstallControllerCustomAction!Citrix.DeliveryServices.InstallControllerCustomAction.CustomActions.RemoveConfiguredFeatures
Begin RemoveConfiguredFeatures
ConfigurationController::RemoveConfiguredFeatures: Removing feature instances.
Exception thrown by custom action:
System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> Citrix.DeliveryServices.PowerShell.Command.Runner.Exceptions.PowerShellExecutionException: An error ocured during running a PowerShell command. ---> System.Exception: Access to the path 'C:\inetpub\wwwroot\Citrix\Roaming' is denied

1. Stop the World Wide Web Publishing Service.

2. Stop all the StoreFront services.

3. Launch the StoreFront installation file as an administrator.