Patching Office365 with Proofing tools fails

Products

• Client Management Suite
• IT Management Suite

Issue/Introduction

You might encounter unexpected behavior when trying to apply updates on office 2019 (Office365) if you have Proofing tools installed - resulting it patch process failing with error 1603.

Environment

ITMS 8.x

Cause

ITMS/Patch Management implementation for Office365 patching is done by parsing contents of https://officecdn.microsoft.com/pr/wsus/ofl.cab and generating download URLs based on its contents.
This is aligned with official recommendation from Microsoft for enterprises that want to update Office 365 from the local CDN (check “Overview of downloading a custom image” section):

https://docs.microsoft.com/en-us/office/client-developer/shared/manageability-applications-with-the-office-365-click-to-run-installer

For example for German this file contains just the following entries:

 <!-- German -->
<File language="1031" relativePath="/office/data/%version%/" name="i321031.cab" languageType="core"/>
<File language="1031" relativePath="/office/data/%version%/" name="i641031.cab" languageType="core"/>
<File language="1031" relativePath="/office/data/%version%/" name="s321031.cab" languageType="core"/>
<File language="1031" relativePath="/office/data/%version%/" name="stream.x86.de-de.dat" hashAlgo="Sha256" hashLocation="s321031.cab/stream.x86.de-de.hash" languageType="core"/>
<!-- End German -->

While during office update, it is looking for sp*.cab files which are not listed as required by MS. 
As far as we can see MS SCCM uses this file as well and looks that Microsoft tools may have a similar problem:

https://answers.microsoft.com/en-us/msoffice/forum/all/proofing-tools-not-working-in-word-office-365/19343a1b-0db3-4a24-bb45-138fa23614a4 

Resolution

At this point of time it's not possible to properly apply Office365 patches on client machines when Office Proofing Tools is installed.