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)

Using Windows Update will result in an Office Online Server that might work – or not. Once it’s done the only way to try to “fix” this Office Online Server is to remove the whole application and reinstall Office Online Server from scratch and install any update before configuring the new farm.

From what I experienced: An Office Online Server, that got updated by Windows Update, can’t be “repaired”. Doing a fresh install of the whole Server (OS and Office Online Server) is the only way.

Update Office Online Server without any preparations

Running the Cumulative Update package just as any other update will brick or at least damage your Office Online Server heavily.

What I have learned: The installer won’t notify you about not fulfilling the prerequisites and the installation  will succeed, but Office Online Server is damaged afterwards. What the exact damage will be – I can’t say. In my case I was no longer able to view or edit any Word Documents.

How to update Office Online Server

Step 1: Save the current configuration and backup the whole server

Before doing anything, save your current configuration.

Get-OfficeWebAppsFarm > c:\OfficeOnlineServer.txt

Running this line of code will result in a text file with your whole Office Online Server configuration.

Finally backup the whole server to be prepared 🙂

Office Online Server with Excel Online:

Just to be on the save site, I would also run the following cmdlets to have a backup of the Office Online Server BI settings: (BI ServerUser defined functions)


Alternative: Find your initial Office Online Server Setup Script

If your initial Office Online Server Setup Script is still available: get it! This will save you a lot of work

Step 2: Prepare your Office Online Server setup and configuration script

Skip this step if you are having your initial setups scripts.

Compare your current Farm settings with the optional switches for this cmdlet and prepare the script to re install your farm after the update.


For a full list of parameters see the technet section Parameters.

Step 3: Apply updates to the (first) server

Plan the availability of your Office Online Server Farm

  • If you are in a single server environment, removing the server  equals a complete destruction of Office Online Server. Office Online Server is not available during the update.
  • If you are in multi server environment, keep in mind to update your load balancing according to your upgrade process. Remove the server-to-be-updated from the loadbalancing group.

Remove the (first) server

  1. On the Office Online Server open the Windows PowerShell as an administrator and run:
  2. Install the Office Online Server update on that server and do a restart.
  3. Restart the server (if prompted)

Create a new farm

After running the update you have to create a new Office Online Server Farm.

  1. Run your Office Online Server Script you created in Step 2

Update the remaining servers

In a multi Office Online Server Farm update your load balancer configuration and start to update the remaining servers by:

  1. Remove the Server from the farm
  2. Skip if you are installing an update obtained from Microsoft Update. If this is a new release of Office Online Server, then you must uninstall the existing version before you install the new version.
  3. Run the update installer
  4. Restart the server
  5. Join the server to updated Office Online Server Farm
    New-OfficeWebAppsMaschine -MachineToJoin ""

Step 4: Compare the settings



and compare the output to the file generated in step 1.

Further more:

  1. test your load balancing (if applicable)
  2. test all Office Online Server functions
    1. with SharePoint
    2. with Exchange

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