I have completed a few Skype for Business installs lately and have had to revisit to apply the Skype for Business Cumulative Update and wanted to put the steps taken here for reference.
1 Check the topology replication status to ensure that replication is working and all is in sync. This is done by either checking the Skype for Business Control Panel or running the ‘Get-CsManagementStoreReplicationStatus’ from PowerShell and confirming.
2 Then check the list of the upgrade domains for the Enterprise Edition pool that is associated with a front-end server. To do this, run the ‘Get-CsPoolUpgradeReadinessState’ cmdlet on a front-end server.
This will confirm what is ready.
Should a front-end server be offline a screenshot similar to this is shown:
3 Run ‘Get-CsWindowsService’ to get an idea of how many conferences and calls are currently running on the server that is going to get the update. Wait a while if there are many in progress on the front-end server.
4 Run the ‘Invoke-CsComputerFailover -ComputerName <Computer.FQDN>’ command next to take the server offline ready for updating.
5 There is a pre-requisite of removing two already installed updates before doing this in order to prevent an issue with the RTCSRV service not starting.
Skype for Business Server 2015, Core Components (KB3051958) with version 6.0.9319.55
Skype for Business Server 2015, Front End Server (KB3061059) with version 6.0.9319.55
Once the Invoke-CsComputerFailover has completed, confirm services are stopped and disabled. The World Wide Web Publishing Service not shown here also is stopped and disabled.
6 Time to run ‘SkypeServerUpdateInstaller.exe’ and click Install Updates
7. Reboot the server if needed
8. After reboot get the front-end server back up and running and part of the pool again.
Run the following command:
‘Invoke-CsComputerFailback –ComputerName <Computer.FQDN>’
9. Once the command has successfully ran, confirm successful replication.
10. Repeat the process on the other 2 front-end servers starting with ‘Get-CsPoolUpgradeReadinessState’ once again.
12. Don’t forget to apply the CU to the Skype for Business Edge Pool Servers
All the best!