When Apple updated High Sierra to version 10.13.4 many Mac users started seeing a warning that indicated that the app wasn’t optimised and that the developer needed to update it to improve compatibility.

Understandably some users are concerned that it means that their apps will stop working. In this article we will look at whether there is cause for concern as well as how to find out which of your apps are 32-bit.

The last time there was this much upheaval in terms of non-compatible apps was when Apple stopped shipping Rosetta in Mac OS X 10.7 Lion. Rosetta was Apple’s tool for translating apps to run on an Intel processor. When Apple initially moved to Intel, Rosetta served to translate legacy apps, but following the release of Lion those old apps were no longer supported.

Why Apple's warning customers about compatibility

Mac users have started seeing warnings, stating that a app ‘is not optimised for your Mac’. The alerts started appearing in early April 2018. If a user opened an app that is currently 32-bit they will see the alert.

The alert looks like this:

The alert suggests that “This app needs to be updated by its developer to improve compatibility”.

The warning doesn’t state that the apps won’t work - just that the developer needs to “improve compatibility”. However, this is misleading because Apple has previously stated that it will end support for 32-bit apps - and that the apps producing the warning are 32-bit apps.

Users will still be able to open the app - at least for now. Understandably the message has left some consumers concerned about the future of apps that they rely on.

Why Apple is ending support for 32-bit apps

Understandably, those people reliant on 32-bit apps are concerned. Will Apple delete their 32-bit apps? While they won’t be deleted, it looks likely that those apps won’t run in the next version of macOS, Apple’s reason is that they won’t offer a good user experience because they slow down your Mac.

Apple has a webpage dedicated to explaining its reasons to stop support for 32-bit apps on the Mac.

The company explains that 64-bit apps can access more memory and therefore you can expect faster system performance.

Apple says: “To ensure that the apps you purchase are as advanced as the Mac you run them on, all future Mac software will eventually be required to be 64-bit.”

When will Apple end support for 32-bit apps on the Mac?

The company doesn’t actually specify a date by when support for 32-bit app on the Mac will end, but it is expected to happen in conjunction with the arrival of the next version of macOS - macOS 10.14 which we cover in detail here.

However, developers have known for some time that support for 32-bit apps would stop in 2018. Apple first announced the move away from 32-bit apps at WWDC in 2017, stating that macOS High Sierra "will be the last macOS release to support 32-bit apps without compromise."

Apple also reminded developers back in December 2017 that from January 2018, new apps submitted to the Mac App Store should include 64-bit support. At the time Apple stated that existing apps have until June 2018 to prepare their 64-bit apps.

This isn’t the first time Apple has ended support for 32-bit apps - in 2017 the company ended support for 32-bit apps in iOS 11. In that case, the transition away from 32-bit apps on the iPhone and iPad actually started in 2015, when Apple had specified that new apps should include 64-bit support. With that much notice, fewer apps should have been affected by the transition, but that didn’t stop people seeing an error message that stated that “This app will not work with future versions of iOS. The developer of this app needs to update it to improve its compatibility.”

Read about that here: Which apps won't work in iOS 11?

Will developers rewrite their apps for 64-bit macOS?

It would appear that Apple is hoping that by drawing attention to the compatibility issue at this early date it will encourage developers to get 64-bit versions of their apps ready.

The concern is that developers may choose to end support for their apps on the Mac rather than re-write them as 64-bit apps. In fact, news that it may be possible to write one app to run across the next versions of iOS and MacOS may cause developers who have a separate iOS and macOS version of their apps to bide their time until Apple releases more information about these plans. Read more about the next version of macOS here.

Which apps will stop working on macOS?

Understandably, consumers are concerned that the message they are seeing indicates that the app could stop working. This could be a major concern for some businesses.

Here are some other non-64-bit applications that may be a cause for concern:

  • Adobe Illustrator CS5
  • Abobe InDesign CS5
  • Microsoft Excel 2011
  • Microsoft PowerPoint 2011
  • Microsoft Outlook 2011
  • Microsoft Word 2011

How to check for 32-bit apps on a Mac

If you want to get ready for the transition to 64-bit apps this autumn, you can check to see if any of your apps are 32-bit now. Here’s how to use MacOS to identify 32-bit apps:

  1. Click on the Apple logo in the left corner of your Mac screen
  2. Choose About This Mac
  3. Click on System Report
  4. Now click on Software > Applications
  5. Look to see whether the apps you use are listed as 64-bit application in the final column.
  6. Any apps that are listed as 32-bit may stop working if you update to macOS 10.14 when it launches in September 2018.
  7. Click on the column that’s headed ’64-Bit’ to see which apps aren’t ready for the transition.

Which Macs can run 64-bit apps

Apple says all modern Macs have a 64-bit processors and can run 64-bit apps.

There has actually been support for 64-bit applications on machines with 64-bit processors since Mac OS X Tiger (Mac OS X 10.4, 2005). Most of Apple’s apps have run in 64-bit since Snow Leopard (Mac OS X 10.6, 2009).

These Macs used the 64-bit kernal by default:

  • Mac Pro (Mid 2010)
  • MacBook Pro (Early 2011)
  • iMac (21.5-inch and 27-inch, Mid 2011)

These Macs could use the 64-bit kernal, but not by default:

  • Mac Pro (Early 2008) and later
  • Mac mini (Mid 2010)
  • iMac (Early 2008) and later
  • MacBook Pro (Early 2008 through Mid 2010)

So, as long as your Mac is newer than one of these, you should be ok. Of course, MacOS High Sierra requires the following speced Macs, so this might be a more accurate run down of the Macs that are equipped to run 64-bit apps when the successor to High Sierra launches.

  • MacBook (Late 2009 or newer)
  • MacBook Pro (Mid 2010 or newer)
  • MacBook Air (Late 2010 or newer)
  • Mac mini (Mid 2010 or newer)
  • iMac (Late 2009 or newer)
  • Mac Pro (Mid 2010 or newer)

What can I do to make sure my apps continue to work?

Wondering what you can do to make sure that your apps don’t stop working later in 2018? Here are our tips:

  • Contact the app developer.
  • Don’t update to macOS 10.14 - the version of the MacOS that will follow High Sierra.
  • Consider transitioning to a different app, or upgrading to a newer version.