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. Now, two generations of macOS later, that warning has reached its culmination in macOS Catalina, which finally marks the end of unoptimised apps.

Understandably some users are concerned that if they update to macOS Catalina, 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 main reason why some apps will no longer work in macOS 10.15.

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 apps aren't optimized

Mac users have been seeing warnings, stating that a app ‘is not optimized for your Mac’ for years now. The alerts started appearing in early April 2018. If a macOS High Sierra or Mojave user opens an app that is 32-bit they will see an alert.

The 'not optimized for your Mac' 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 ended support for 32-bit apps in macOS Catalina (which launched in October 2019) - and the apps producing the warnings are 32-bit apps.

If you need to use these apps you will still be able to open the app but only if you are running High Sierra or Mojave. If you update to Catalina then those apps will no longer work. Understandably some consumers are concerned about the future of apps that they rely on.

Apple's 'App needs to be updated' warning

If you have updated to macOS Catalina then it should be no surprise that those apps that you were seeing warnings about in Mojave and High Sierra no longer work.

If you try to open one of these apps then you will see a warning that the app 'Needs to be updated', with the description: "The developer of this app needs to update it to work with this version of macOS. Contact the developer for more information.

app alert in Catalina

If you see this warning and need to run the app you really only have two choices. Either you update the app to a 64-bit version - it's likely that there is one but you will probably have to pay to update your software, which may be why you hadn't done so. Or, you can downgrade to Mojave, or run Mojave in a separate volume on your Mac.

Why Apple has ended support for 32-bit apps

Understandably, those people reliant on 32-bit apps are concerned. 32-bit apps will not run in macOS Catalina, 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 said: “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.”

Developers have known for some time that support for 32-bit apps would stop in 2019. Apple first announced the move away from 32-bit apps at WWDC in 2017, stating that macOS High Sierra "would be the last macOS release to support 32-bit apps without compromise." Mojave did continue to support those apps, but essentially: 'with 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 had 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 on the iPhone and iPad 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.”

Will developers rewrite their apps for 64-bit macOS?

It would appear that Apple hoped that by drawing attention to the compatibility issue at this early date it would 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.

Alternatively, news that Apple is making it easier 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 may choose to focus on the iOS version and then port that to the Mac instead.

Do I need to update my apps then?

The real issue is Mac users willingness to update outdated apps. The most likely scenario is that it's the Mac user who needs to update their apps to a newer version. If you are still using old versions of Microsoft Office or Adobe Creative Suite (Photoshop, In Design, Illustrator and so on) for example, then it may be time to finally bite the bullet and update. That's if you are willing to pay for a subscription - which is the model that many of these suites of apps now use. If you prefer not to fix yourself in to a monthly subscription to keep your apps up to date then perhaps a better alternative would be to look for an alternative to Photoshop or Word, for example.

Which apps will stop working on macOS Catalina?

Here are some 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

For more information read: Apps that won't work in Catalina.

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.

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? Here are our tips:

  • Contact the app developer.
  • Don’t update to macOS 10.15 Catalina.
  • Consider transitioning to a different app, or upgrading to a newer version.