With many of my post I try to write about items I do not find discussed anywhere else. This topic has actually been mentioned before and is a little older issue. What I find interesting is Microsoft has not taken any action to remedy the bug. It is a very quick fix, but this information should be stated in the KB article as a known issue. I’m betting a few Lync Admins have spent several hours resolving this issue after patch night.
While troubleshooting an issue where PowerPoint presentations had stopped working for Lync users I noticed the OWA server was not listed in the Machines field after doing a Get-OfficeWebAppsFarm command.
Additionally you will see certain Errors logged in the Application Logs section of the Event Viewer.
It seems after installing the patch KB2810007 the OWA machine is removed from the OWA Farm. The latest OWA image of this writing is still the old version and does not have the update included. To fix this issue recreate the farm with the New-OfficeWebAppsFarm command: for example New-OfficeWebAppsFarm -InternalUrl https://server.contoso.com -ExternalUrl https://wacweb01.contoso.com -CertificateName “OfficeWebApps Certificate” -EditingEnabled
If for some reason you had two servers and one was still listed you could add the updated server back by simply running the same command with the –MachineToJoin switch; New-OfficeWebAppsFarm -MachineToJoin <UpdatedServer>.
When deploying Office Web Apps using the affected image file, be sure to update the system before creating the Farm to avoid this issue.
KB2810007 Update for Microsoft Office Web Apps Server 2013 originally came out on April 4th 2013.
KB2760445 Update for Microsoft Office Web Apps Server 2013 originally released on March 8th 2013, also causes this issue.
As with all updates they should be tested before applying; I know in many environments this is not always possible. As such it is a good idea to assume any future updates to Office Web Apps Server 2013 will also cause this issue and should be verified after applying an update.