Existing Office 2016 for Mac customers will be seamlessly upgraded to 64-bit versions of Word, Excel, PowerPoint, Outlook, and OneNote as part of the August product release (version 15.25). This affects customers of all license types: Retail, Office 365 Consumer, Office 365 Commercial, and Volume License installations.
Deployment options for the 64-bit update
Customers who use Microsoft AutoUpdate (MAU) to keep their Office applications up-to-date will see a "regular" monthly update notification when their selected channel is upgraded to 64-bit builds. Depending on which version is installed on the local computer, MAU will offer either a delta or full update. The update package size does not change between 32-bit and 64-bit versions. Also, MAU can deliver a delta update when applicable to update a user from 32-bit to 64-bit applications. Therefore, customers won’t experience a sharp increase in download activity. For the release to the Production channel, customers will see "(64-bit)" in the update title to make them aware that this is a 64-bit update.
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Volume License Service Center
Volume License customers typically get their Office 2016 software from the Volume License Service Center (VLSC). These builds are refreshed infrequently and are typically aligned with new language editions. The VLSC will continue to offer 32-bit installers (15.23) until November 2016. However, all updater packages that are released after August will be based on 64-bit builds. Therefore, a VLSC customer who updates either manually or through AutoUpdate will be transitioned to 64-bit builds.
The Mac operating system has been 64-bit for several years. Unlike for Windows, there's no choice between running a 32-bit or 64-bit version of the Mac operating system. Similarly, we won't offer a choice between 32-bit and 64-bit versions of Office 2016 for Mac. After each "channel" is transitioned per the rollout schedule, only 64-bit builds will be available.
Effect on third-party applications and add-ins
The transition to 64-bit Office for Mac was announced on the Office developer blog in April 2016. This website is the primary reference for third-party vendors to understand the change and the effect on their products. IT Pros will want to understand which compiled add-ins are deployed to the users whom they manage so that they can assess the effect of the upgrade. The following Microsoft Office website summarizes the issues that affect the more common add-ins that are used together with Office 2016 for Mac:
To verify the architecture of an Office application (that is, to understand whether you have a 32-bit or 64-bit build), start the application, open the Activity Monitor, and then enable the Kind column.
You can also use the file command in a terminal session to inspect the binary. For this use, type file -N <path of binary>. This method can be used with for any binary file, including third-party add-ins.
FAT binary (compatible with both 32-bit and 64-bit processes)
Options for reverting to 32-bit installations
There may be situations in which the customer has to change code that's not 64-bit ready. If customers can't immediately move forward to 64-bit builds, we will make available a one-time 32-bit update for the 15.25 release in addition to the default 64-bit updates. The 32-bit updates will be available only for manual download from the Office CDN.
Customers who manually install the 32-bit release won't be offered the 64-bit version of 15.25 through MAU. However, MAU will offer the 64-bit version of 15.26 in September 2016. Therefore, customers have a limited time to remain on 32-bit builds.
If a customer has already upgraded to the 64-bit update of Office for Mac 15.25 and wants to revert to the 32-bit version, follow these steps: