Q:

Wix installer.  How to stop IIS pool

I faced with the problem in my WIX installer: how can I stop specific IIS application pool during repair, change or update? 
Description: Deliver and deploy Web Application, run repair.  Dialog appears that says that w3wp process locks files.  In addition, because of requirements I cannot just hide that message and I cannot change Web Application. 

What I tried to do:

I tried to stop service "W3SVC" with ServiceControl and it works excellent!  But what I really need to do is to stop only one specific IIS pool. 
I consider the way to write my own custom action to stop app pool, but as I know, I cannot schedule it before InstallValidate.  Please, correct me if I'm wrong. 

Please, help me overcome this issue. 

A:

You can use quiet execute custom action to shell out to appcmd to stop an app pool.  You are right though, you wouldn't always be elevated prior to InstallValidate. 
https://technet.microsoft.com/en-us/library/cc732742(v=ws.10).aspx
I suspect this is probably a false alarm and will resolve itself later in the installer.  I would look at the various was to suppress this dialog.  Maybe this would help:
WiX: Avoid showing files-in-use dialog and just prompt for reboot at end of install

