How to change the Office Web Apps / Office Online Server Certificate

Changing certificates is a simple task – not very demanding – but in case of Office Web Apps and Office Online Server there is more to do. I will use Office Online Server as a synonym for Office Web Apps in the article. There is no difference in the process.

Before you change the IIS certificate, hold in, and think about the Office Online Server Farm setup:

Remember this command?

Set-OfficeWebappsFarm -CertificateName "YourShinyNewCertificateFriendlyName"

You will need to run this command to set the new certificate for your Office Online Server farm. But, before you start right way, please make sure these conditions apply:

  • Be sure, that the certificate is installed on every server in your Office Online Server Farm
  • Be sure, that the friendly name of the certificate is set to the same value on each server



How to update Office Online Server

Updating Office Online Server is not as easy as you would expect. It does require some efforts in planning and doing. This technet article is very well written: Apply software updates to Office Online Server. I want to share my experience on updating Office Online Server as there are many pitfalls on the way!

Warning! Do not:

use Windows Update

“Applying Office Online Server updates by using the automatic updates process isn’t supported with Office Online Server. This is because updates to an Office Online Server must be applied in a specific way, as described in this article.” (Source: Apply software updates to Office Online Server)

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Office Online Server – MSVCR120.dll missing

Today I installed a new Office Online Server Farm based on two Windows 2012 R2 Servers.

The installation went smooth, but I experienced an unhealthy farm status. Checking the ULS logs I found the following error:

LoadLibrary failed with error 2 on D:\Program Files\Office Web Apps\OneNoteMerge\bin\ONSrvU.DLL

After a bit of investigation, I tried to run the OneNoteMerge.exe. This resulted in the following error:

The program can't start because MSVCR120.dll is missing from your computer.
Try reinstalling the program to fix this problem.

What now?

Checking the c:\windows\system32\ folder I found the following file:


Following the Microsoft Deployment Guide for Office Online Server there are the following prerequisites:

  • .NET Framework 4.5.2 (I wasn’t able to install it)
  • Visual C++ Redistributable for Visual Studio 2015
  • Microsoft.IdentityModel.Extention.dll

I install the remaining two prerequisites, but wasn’t able to get rid of the errors.

I found the following article: Determining Which DLLs to Redistribute pointing out, that msvcr120.dll is a part of Visual Studio 2013.

So I went for the Visual C++ Redistributable Packages for Visual Studio 2013 package and downloaded both the x64 and x86 version and installed them. The msvcr120.dll comes with the x64 version.

This solved the error for me. I hope it works in your environment as well.