
If you are like my unfortunate client, your installation of Office Web Apps (or WAC) was humming along just fine until that one day comes that you wish you never got out of bed. This turned out to be a simple fix but took some hair-pulling to get there, so let me share my journey.
The Errors
For the record, this server was Office Web Apps 2013 and this was the only server hosting the WAC farm. We saw a lot of symptoms for this problem and they included:
- SharePoint would not render any previews of Office documents, nor could you open any files in Office in the browser. It gave the the error “This page could not be displayed”.
- Attempting to open the URL for Office web apps like https://<WAC URL>/hosting/discovery gave the same error “This page could not be displayed”.
- The output of Get-WOPIZone on the SharePoint server looked fine.
- On the WAC server, the Office Web Apps server would not start. It would log this Event ID 0 error in the Event logs: “Service cannot be started. System.IO.IOException: The process cannot access the file ‘C:\ProgramData\Microsoft\OfficeWebApps\Data\local\ULSConfig\Uls.Config.Dynamic.xml’ because it is being used by another process.”
- After a server reboot and using Process Explorer to kill some processes, it would give this error when trying to start: “Service cannot be started. System.InvalidOperationException: The certificate has not been specified.”
- On the WAC server in the Microsoft Office Web Apps event log would be these errors:
- Error when trying to connect to Farm State Manager service: System.ServiceModel.EndpointNotFoundException: There was no endpoint listening at http://azrvspwa01:809/farmstatemanager/FarmStateManager.svc that could accept the message. This is often caused by an incorrect address or SOAP action.
- There was a pre-existing event for the UlsController service. Trying to signal and reset.
- Could not provision HTTPS endpoint because the certificate was not specified, not found, or invalid.
- The certificate specified in farm settings was not found in the store.
- On the WAC server, any Office Web Apps powershell you would run would give the error “It does not appear that this machine is part of an Office Web Apps Server farm.” This includes Get-OfficeWebAppsFarm, Set-OfficeWebAppsFarm, etc.
- On the WAC server, all IIS websites and application pools were started.
Wow that’s a lot of errors! But luckily for us, they all stem from one cause. After you review all of the errors, you can take a guess – the SSL certificate.
The Fix
This Office Web Apps installation was set to use SSL, not HTTP. I went and looked into the certificate store, and I could not see the cert named what I expected from my install notes. Our main problem now is that I can’t run any powershell or start the OWA service because the certificate that I did find that showed for the URL of the WAC server expired about 2 weeks before. We’re on to something!

My IT contact issued a new certificate into the Personal Store of the WAC server and gave me the name of the cert. You want the “Friendly Name” of the cert.

Next I went and edited the following file so we can update the SSL certificate name under the covers:
C:\ProgramData\Microsoft\OfficeWebApps\Data\FarmState\settings.XML
Edit the line for CertificateName, and update the value matching the certificate’s friendly name.

Save that, and then try to start the OWA Windows Service. Success! Now go check everything else like PowerShell, more success! Just for good measure, I ran the following commands just to be safe:
- Import-Module -Name OfficeWebApps
- Set-OfficeWebAppsFarm -certificatename ‘WC_2020’
The ultimate test is to go back and check the discovery URL from before.

We are in business! We went back and checked SharePoint and now all the previews were working too. I didn’t have to re-create the WAC farm or the WOPI connection to it! Sure hope this helps someone else avoid some hours of aggravation.
If you need help with your Office Web Apps install or prepare for SharePoint 2019, contact us!