What’s with All These Dialogs Saying, “SomeApp is not optimized for your Mac”?

If you’re running macOS 10.13.4 High Sierra or macOS 10.14 Mojave, you may have seen a dialog that says an app isn’t optimized for your Mac. The message differs slightly between High Sierra and Mojave, with the High Sierra version telling you the developer needs to update the app to improve compatibility whereas Mojave saying bluntly that the app won’t work with future versions of macOS.

This may not be something you need to address immediately, but I have a lot of questions from clients about this so I wanted to clear it up. If you are reading this on your iPhone or iPad, you can just hold the Siri button and say “Remind me about this page in August” so that you can reference this again before the fall updates are released.

What’s going on here, what should you do, and when should you do it?

What’s Going On: 32-bit and 64-bit Apps

Over a decade ago, Apple started to transition all the chips used in Macs, along with macOS itself, from a 32-bit architecture to a 64-bit architecture. Without getting into technical details, 64-bit systems and apps can access dramatically more memory and enjoy significantly faster performance.

Apple knew it would take years before most people were running 64-bit hardware and 64-bit-savvy versions of macOS, so it allowed macOS to continue running older 32-bit apps. However, maintaining that backward compatibility has a cost, in terms of both performance and testing, so at its Worldwide Developer Conference in 2017, Apple warned developers that High Sierra would be the last version of macOS to support these old 32-bit apps “without compromise.” At the next WWDC in June 2018, Apple announced that macOS 10.14 Mojave would be the last version of macOS to run 32-bit apps period.

Happily, the only “compromise” for 32-bit apps in Mojave is the warning dialog, which appears every 30 days when you launch an older app. But the writing is on the wall: 32-bits apps will cease working entirely in macOS 10.15, likely to be released this September.

How Do You Identify 32-bit Apps?

Apple provides a tool to help you find 32-bit apps, though it takes a little digging. Follow these steps:

  1. From the Apple menu, choose About This Mac and then click the System Report button.
  2. In the System Information utility that opens, scroll down to Software in the sidebar and select Applications. It may take a few minutes to build the list of every app on all mounted drives.
  3. When it finishes, click the 64-bit column header (No means 32-bit; Yes means 64-bit) to sort the list, and select an app to see its details in the bottom pane.

This technique works in both High Sierra and Mojave, but in Mojave, System Information includes a better-formatted section, called Legacy Software, that also provides a list of 32-bit apps. However, this list may be smaller because it includes only those apps that you’ve launched. Since it’s likely that you open old 32-bit apps only occasionally, you can’t trust the Legacy Software list to be complete, but then again, maybe it means that you don’t need to worry about things you haven’t opened in a long time.

If you find System Information’s Applications list overwhelming, check out the free 32-bitCheck utility from Howard Oakley. It performs exactly the same task but lets you focus on a particular folder and save the results to a text file for later reference.

What’s Your Next Step?

Once you know which apps won’t work in macOS 10.15, you can ponder your options. Luckily, you have some time. I expect Apple to release macOS 10.15 in September 2019 based on past patterns, but you don’t need to upgrade right away—in fact, I often recommend that you wait a few months after that to allow Apple time to fix bugs anyway.

That said, I do encourage upgrading eventually, and if you buy a new Mac after September 2019, it will come with macOS 10.15. So you need to establish a plan—it’s better to know what you’re going to do than to be forced into action if you have to replace your Mac on short notice. For each 32-bit app on your Mac, you have three options:

  • Delete it: It’s not uncommon to have old apps that you haven’t used in years and won’t miss. There’s no need to waste drive space on them. Or ignore it. If you don’t use the program and if you aren’t short on space it probably won’t do anything harmful if you leave it there since it won’t be able to run anyway. My favorite tool for deleting apps is AppCleaner. It’s free, lightweight, and doesn’t continually run in the background clogging up your computer. But do check the website for the app you want to remove. Some apps have a built-in uninstaller that will likely be more thorough. A good Google search would be something like “uninstall symantec endpoint protection mac
  • Upgrade it: Apps in active development will likely have a new version available. The main question is how much the upgrade will cost. You can upgrade at any time, although it’s likely worth waiting until you’re ready to move to macOS 10.15 to minimize costs (or when 10.15 is released in case you accidentally upgrade). A lot of developers release major new versions shortly after Apple releases their annual fall upgrades. The apps that cause the most irritation here are things like the Adobe Creative Suite—Photoshop, Illustrator, and InDesign—that require switching to a monthly subscription.
  • Replace it: If no upgrade is available, the cost of upgrading is too high, or upgrading comes with other negatives, it’s time to look for an alternative. This can take some time, so it’s worth starting soon to ensure that the replacement will provide the features you need before macOS 10.15 forces the decision. One of my favorite alternatives to Photoshop is Pixelmator or Pixelmator Pro. And I’ve discussed my favorite Microsoft Office alternatives in the past.

Needless to say, if you’d like recommendations about how to proceed with any particular app or workflow, you may want to book an appointment!