Delta updates for Office 2016 for Mac


Updates for Office 2016 for Mac are released monthly. Until now, each monthly update contained a complete, full copy of the application. This required lengthy download and update times, especially for customers on low-bandwidth connections.

Starting with the Office for Mac update 15.18 release, Microsoft AutoUpdate now offers a smaller "delta update." Delta updates are on average 77 percent smaller than full updates, and this means that download times are much shorter.

Note Delta updates are available only through Microsoft AutoUpdate. The download files that are provided in the corresponding KB articles are full updates. 

How delta updates work

Microsoft AutoUpdate first inspects the Office for Mac version data that's installed on the device. If the installed Office for Mac application is eligible, Microsoft AutoUpdate automatically offers the delta update. The delta update installer performs a file check between particular builds, and this check includes the code signature of the application. The installer then adds new and modified files, removes deleted files, and updates the code signature to retain the security and integrity of the app bundle. 

Q & A

  1. Q. What are the exact size differences between a delta update and a full update?

    A. Using Office for Mac update 15.18 as an example, a full update for all five Office apps comprises a download of 3.34 GB. The corresponding delta update is only 784 MB.
  2. Q. What is the most efficient supportable method for enterprise customers who use third-party deployment solutions (instead of Microsoft AutoUpdate) to perform updates?

    A. Because the suite installer is ~1.3 GB in size, which is considerably smaller than a full update, it's supportable to update an older installation by "reinstalling," using a newer version of the suite installer.
  3. Q. In the case of a hotfix release (for example, where Word is version 15.17.1, and the other apps in the release are version 15.17.0), can a delta update be applied to both the .0 and .1 versions of the package?

    A. Yes. The diffing technology that we use baselines all hotfix releases in the N-1 window. Therefore, in this example, a delta update can be applied to all 15.17.x apps, regardless of hotfix version.
  4. Q. Are there any other technologies available to make downloads faster?

    A. Yes, starting with the 15.17 release in December 2015, we moved all update packages to an Akamai-based global content delivery network (CDN). Before the 15.17 release, updates were stored in the Microsoft Download Center. Many customers have reported significant download improvements because of this change.
  5. Q. Are there any other improvements planned for delta updaters?

    A. Yes. We foresee additional download savings by consolidating per-app delta updates into a suite delta update. This is planned for a future release.


Article ID: 3136098 - Last Review: 2 Feb 2016 - Revision: 1