My Citrix XenApp farm runs with XenApp 5 on Windows Server 2008 64bit servers. I found a strange issue on few XenApp Servers goes to Zombie mode. The server is pingable and operational. No users connected to this server. If you have specific application points to this server, Users get this error message:
It was not possible to launch the selected application.
Please contact your administrator
The Citrix client reported error: 12
If you run “QFarm /Load” on any one of the XenApp server in the farm, load results doesn’t list the zombie server. ‘”Change Logon /Query” command result shows Logon is enabled. I read the available hot fixes and none of them fixes this issue. 
Easy fix is to restart “Citrix Independent Management architecture” aka IMA service on the problematic server. By restarting IMA service you are re-registering the server to the Farm. The load balancing algorithm starts accounting the server after IMA restart.
So I wrote the following script and run it by hour using Windows Scheduler on one of the XenApp server. This script sends emails details report to specified admins when it fixes the zombie server issue. Till I find a permanent fix from Citrix or Microsoft, This script is saving me from aches.
If you want to use this script, copy and paste this script to Notepad. Look for “<<<< Modify the value here..” and change the appropriate values according to your company. Schedule it on one of your XenApp servers.
'======================================================================
' Name: Fix-XenApp-Servers.vbs
' Purpose: Detect if XenApp server is dropped from Load Balancing.
' If Yes, Restart the Citrix IMA server and send email alert.
' Parameters: None
' Written By: Anand Venkatachalapathy
' Date Written: Feb 10th 2010
'======================================================================
Const IMAService = "Citrix Independent Management Architecture"
Dim WshShell, WshExec
Dim LoadData, emailSubject,emailTo,i
Public emailBody
Dim XenAppServers
XenAppServers = Array("CitrixSvr1","CitrixSvr2","CitrixSvr3") '<<<<<<<<< Modify the value here
emailTo = "admin1@company.com;admin2@company.com" '<<<<<<<<< Modify the value here
Set WshShell = WScript.CreateObject("WScript.Shell")
'Run qfarm /load command and get the results to LoadData variable
Set WshExec = WshShell.Exec("qfarm /load ")
LoadData = LCase(WshExec.StdOut.ReadAll)
For i = 0 To UBound(XenAppServers)
'Check if XENAPPxx server is missing
If InStr(LoadData,LCase(XenAppServers(i))) = 0 Then
WScript.Echo XenAppServers(i) & " is not responding"
emailSubject = XenAppServers(i) & " was not responding, IMA service restarted"
emailBody = XenAppServers(i) & " Server was not listed in QFarm /Load command as below" & vbCrLf
emailBody = emailBody & LoadData & vbCrLf & vbCrLf & _
"Trying to fix by restarting IMA service to re-register to the farm" & vbCrLf & vbCrLf
'Restart Citrix IMA service
service_control XenAppServers(i),IMAService,"restart"
Set WshExec = WshShell.Exec("qfarm /load ")
LoadData = LCase(WshExec.StdOut.ReadAll)
emailBody = emailBody & "QFarm /Load results after IMA service restart" & vbCrLf
emailBody = emailBody & LoadData
emailBody = emailBody & vbCrLf & vbCrLf & "--------Written By: Anand Venkatachalapathy------------"
'Send email to Citrix Admins
Alert_Admins emailTo,emailSubject,emailBody
End If
Next
'*** End of Script ***
'==============================================================================
' Name: Service_Control
' Purpose: Restart, Stop or Start a Service on a remote server
' Input: strComputer - Remote Server Name
' sname - Service Display Name
' purpose - has to be "stop" or "start" or "restart"
'==============================================================================
Sub Service_Control(strComputer,sname,purpose)
'strComputer is the computer you want to connect to
'sname is the service name
'purpose is whether or not you want to start, stop or restart a service
Dim delay, err_return
delay = 20000 '20 seconds
WScript.stdout.Write "*"
Set objWMIService = GetObject("winmgmts:" _
& "{impersonationLevel=impersonate}!\" & strComputer & "rootcimv2")
Set colListOfServices = objWMIService.ExecQuery _
("Select * from Win32_Service where DisplayName = '" & sname & "'")
For Each objService In colListOfServices
'Just to double check we have the right service
If objService.displayname = sname Then
WScript.stdout.Write "*"
If purpose = "stop" Or purpose = "restart" Then
emailBody = emailBody & "Trying to stop " & strComputer & "" & objService.name & vbCrLf
err_return = objService.stopservice
'service has dependencies, so we need to stop those first
If err_return = 3 Then
'GOTCHA - you have to use the service.name NOT service.displayname for this query!!
'even if you change Win32_Service.Name to Win32_Service.DisplayName
Set colServiceList2 = objWMIService.ExecQuery("Associators of " _
& "{Win32_Service.Name='" & objService.name & "'} Where " _
& "AssocClass=Win32_DependentService " & "Role=Antecedent" )
For Each objService2 in colServiceList2
emailBody = emailBody & "Trying to stop " & strComputer & "" & objService2.name & vbCrLf
objService2.StopService()
If Not objService2.state = "Stopped" Then
'you have to pause because the service wont start unless it is completely stopped
WScript.Sleep delay
service_control strComputer,sname,"stop"
Else
'WScript.Echo objService2.displayname & " has been stopped."
emailBody = emailBody & strComputer & "" & objService2.name & "has been stopped." & vbCrLf
End If
Next
'stop the original service that had dependencies
emailBody = emailBody & "Trying to stop " & strComputer & "" & objService.name & vbCrLf
objService.stopservice
Else
If Not objService.state = "Stopped" Then
'you have to pause because the service wont start unless it is completely stopped
WScript.Sleep delay
service_control strComputer,sname,"stop"
Else
'WScript.Echo objService.displayname & " has been stopped."
emailBody = emailBody & strComputer & "" & objService.displayname & " has been stopped." & vbCrLf & vbCrLf
End If
End If
'if restart was sent, start service after it has stopped
If purpose = "restart" Then service_control strComputer, sname, "start" End if
Elseif purpose = "start" Then
WScript.stdout.Write "*"
emailBody = emailBody & "Trying to start " & strComputer & "" & objService.name & vbCrLf
err_return = objService.startservice
If NOT err_return = 10 Then
'GOTCHA - you have to use the service.name NOT service.displayname for this query!!
'even if you change Win32_Service.Name to Win32_Service.DisplayName
Set colServiceList2 = objWMIService.ExecQuery("Associators of " _
& "{Win32_Service.Name='" & objService.name & "'} Where " _
& "AssocClass=Win32_DependentService " & "Role=Antecedent" )
For Each objService2 in colServiceList2
emailBody = emailBody & "Trying to start " & strComputer & "" & objService2.name & vbCrLf
objService2.StartService()
If Not objService2.state = "Running" Then
'you have to pause because the service wont start unless it is completely stopped
WScript.Sleep delay
service_control strComputer,sname,"start"
Else
WScript.Echo objService2.displayname & " has been started."
emailBody = emailBody & strComputer & "" & objService2.displayname & " has been started" & vbCrLf
End If
Next
emailBody = emailBody & "Trying to start " & strComputer & "" & objService.name & vbCrLf
err_return = objService.startservice
'service has dependencies, so we need to start those first
If err_return = 3 Then
'start the original service that had dependencies
emailBody = emailBody & "Trying to start " & strComputer & "" & objService.name & vbCrLf
objService.startservice
'End If
If Not objService.state = "Running" then
'you have to pause because the service wont start unless it is completely stopped
WScript.Sleep delay
service_control strComputer,sname,"start"
Else
'WScript.Echo objService.displayname & " has been started."
emailBody = emailBody & strComputer & "" & objService.displayname & " has been started." & vbCrLf
End If
End If
End If
'WScript.Echo objService.displayname & " has been started."
emailBody = emailBody & strComputer & "" & objService.displayname & " has been started" & vbCrLf
End If
End If
Next
End Sub
'*** End of service_control sub ***
'======================================================================
' Name: Alert_Admins
' Purpose: Sends email
' Input: strTo - Who to send to, strSub - Subject of the message
' strBody - Body of the message
' Output: Sends the emails to the strTO recipients
'======================================================================
Sub Alert_Admins( strTo,strSub,strBody)
'WScript.Echo strBody
'* iMsg - holds CDO.Message object
'* Flds - Enumeration for CDO SMTP object properties
'* iConf - holds CDO.Configuration
Dim iMsg, Flds, iConf
'* sSMTPServerName - SMTP Server Name
Dim sSMTpServerName
'* Assign corpml servers as SMTP server
sSMTPServerName = "smtp.company.com" '<<<<<<<<< Modify the value here
'* Assign cdoSendUsingPort is set to 2, i.e., send using SMTP (25) port
Const cdoSendUsingPort = 2
'* Create CDO Objects and assign to variables
Set iMsg = CreateObject("CDO.Message")
Set iConf = CreateObject("CDO.Configuration")
Set Flds = iConf.Fields
'* Assign values to Flds class properties
With Flds
.Item("http://schemas.microsoft.com/cdo/configuration/sendusing") = cdoSendUsingPort
.Item("http://schemas.microsoft.com/cdo/configuration/smtpserver") = sSMTPServerName
.Item("http://schemas.microsoft.com/cdo/configuration/smtpconnectiontimeout") = 25
.Update
End With
'* Assign message properties and Send the mail
With iMsg
Set .Configuration = iConf
.Fields("urn:schemas:httpmail:importance").Value = 2 'Setting Mail importance to High (2)
.Fields.Update
.To = strTo
'Fake, but make-sense email FROM address
.From = "XenApp-Fixer@company.com" '<<<<<<<<< Modify the value here
'Return Email address
.Sender = "XenApp-Fixer@company.com" '<<<<<<<<< Modify the value here
.Subject = strSub
.TextBody = strBody
.Send
End With
End Sub
'*** End of Alert_Admins Sub ***
Anand, the Architect 
I just tried this on one of our XenApp 5 Win2K8 R1 x64 servers. It found a server that is not responding, however after that popup is shown, I get a Windows Script Host error (code 80070006) stating “The handle is invalid.” (Line 71 Char 5).
Do you know what the issue may be?
I think I missed to specify run the script in elevated mode (or in elevated command prompt).
I am a novice scripter, mainly dealing with batch files. Can you please let me know what I need to do to resolve the issue?
Not sure if this is what you meant, but I launched cmd via Run as administrator and this was the output (T3PTerm13 has logons disabled):
D:\admin>xenapp-fixer.vbs
Microsoft (R) Windows Script Host Version 5.7
Copyright (C) Microsoft Corporation. All rights reserved.
T3PTerm13 is not responding
*D:\admin\XenApp-Fixer.vbs(72, 5) (null): 0x8004100E