While upgrading one of my existing Exchange 2010 lab machines from RTM to SP1, I encountered the following error message during the upgrade:

Error:
The following error was generated when "$error.Clear();
          if (!(get-service MSExchangeADTopology* | where {$_.name -eq "MSExchangeADTopology"}))
          {
            install-ADTopologyService
          }
        " was run: "There are no more endpoints available from the endpoint mapper. (Exception from HRESULT: 0x800706D9)".
There are no more endpoints available from the endpoint mapper. (Exception from HRESULT: 0x800706D9)

The message appeared at the stage of upgrading the Unified Messaging components. I had a look at the ExchangeSetup.log file and it contained the the following information:

[08/27/2010 10:08:13.0948] [2] Beginning processing install-UMService
[08/27/2010 10:08:14.0011] [2] [WARNING] An unexpected error has occurred and a Watson dump is being generated: There are no more endpoints available from the endpoint mapper. (Exception from HRESULT: 0x800706D9)
[08/27/2010 10:08:14.0027] [2] [ERROR] There are no more endpoints available from the endpoint mapper. (Exception from HRESULT: 0x800706D9)
[08/27/2010 10:08:15.0823] [1] The following 1 error(s) occurred during task execution:
[08/27/2010 10:08:15.0823] [1] 0.  ErrorRecord: There are no more endpoints available from the endpoint mapper. (Exception from HRESULT: 0x800706D9)
[08/27/2010 10:08:15.0823] [1] 0.  ErrorRecord: System.Runtime.InteropServices.COMException (0x800706D9): There are no more endpoints available from the endpoint mapper. (Exception from HRESULT: 0x800706D9)
at Interop.NetFw.INetFwRules.Add(NetFwRule rule)
at Microsoft.Exchange.Security.WindowsFirewall.ExchangeFirewallRule.Add()
at Microsoft.Exchange.Configuration.Tasks.ManageService.Install()
at Microsoft.Exchange.Management.Tasks.UM.InstallUMService.InternalProcessRecord()
at Microsoft.Exchange.Configuration.Tasks.Task.ProcessRecord()
at System.Management.Automation.CommandProcessor.ProcessRecord()

It seems the error is caused while trying to add a firewall rule, indicated by Interop.NetFw.INetFwRules.Add (INetFwRules is the rules collection of the built-in Windows Firewall).

I had a quick check with the firewall settings on the machine and it turned out the Windows Firewall was disabled. I figured that perhaps adding the rules failed because setup couldn’t communicate with the firewall service.

I enabled the Windows Firewall and this time the upgrade process went fine:

[08/27/2010 10:23:10.0988] [2] Beginning processing install-UMService
[08/27/2010 10:23:11.0145] [2] Ending processing install-UMService