An old app won't open after a macOS upgrade

Why it happens

Each macOS version drops support for some older app code. Apps built only as 32-bit apps stopped working years ago, and some apps have no version for your Mac's chip. Only the developer can fix this with an update, so the answer is a newer version of the app.

How to fix it

1. If the app came from the App Store, open the App Store and click Updates in the sidebar. Click Update next to the app if it's listed.

   App Store›Updates

2. If it didn't come from the App Store, visit the developer's website and download the latest version for macOS 26 or 27. Install it over the old one in Applications.

3. Not sure how old the app is? Select it in Applications, choose File > Get Info, and look at Kind and Version. Compare that with the newest version on the developer's site.

   File›Get Info

4. If there's no newer version, write to the developer and ask whether one is planned. Until then, look for another app that does the same job.

Still not fixed?

1. If your Mac offers to install Rosetta when you open the app, click Install. The app is built for Intel Macs, and Rosetta lets it run on Apple silicon on macOS 26 and 27. Ask the developer for an Apple silicon version, since Rosetta won't be around forever.

2. Updated the app and it still won't start? Restart your Mac and try again. If it opens and closes straight away, delete it from Applications and install a fresh copy.

3. Need the old app for files you can't open anywhere else? Open them in the app on another Mac that still runs an older macOS, and save them in a common format such as PDF.

4. If an app from Apple itself says it isn't compatible, check Software Update for a macOS update first, then contact Apple Support.