Exchange 2010 SP2 upgrade error

I was performing an SP2 upgrade on a clients Exchange 2010 Sp1 environment today and whilst upgrading the first “Mailbox Server Role” in the DAG the upgrade process came up with the following error:-

Error:
      The following error was generated when “$error.Clear();
             if ($exsSid -eq $null -or $exsSid -eq “”)
            {
            $exsSid = get-ExchangeServerGroupSID -DomainController $RoleDomainController
            }
           start-setupservice -ServiceName MSExchangeADTopology -ServiceParameters      
           $exsSid,$RoleDomainController ” was run: “Service ‘MSExchangeADTopology’ failed to reach status ‘Running’ on this server.”. 

Service ‘MSExchangeADTopology’ failed to reach status ‘Running’ on this server.

Looking at the exchange setup logs it was discovered that the Exchange Trusted Subsystem was not a member of the Builtin Administrators group.

To add use the following procedure: –

1. Open Active Directory Users and Computers
2. Under domain name (For example contoso.com), locate the Builtin Container, and on
   the right hand side select the Administrator group.
3. Go into properties of the group
4. Click members tab and add Exchange Trusted Subsystem
5. Click ok twice
6. Reboot the Exchange server
7. Rerun the Exchange setup

This time round the upgrade worked fine and the remaining Mailbox servers updated without error.