How to fix a macOS App Store ‘Cannot Update App’ error

Apple cryptographically encodes into every app downloaded the Apple ID of the purchaser. That’s true with “free” apps (truly free or free with in-app purchases) and paid ones alike, including Apple’s own software, such as Pages and GarageBand.

You can wind up with the above error in a few cases: you purchased a Mac with software already installed and try to update it, or you changed the Apple ID used for purchases on your Mac. Other more obscure conditions may apply, but they’re not documented. (If you didn’t purchase an app that’s installed on a Mac you bought or were given, there’s no way to receive updates without the original Apple ID login.)

The solution is quite easy:

1. Find the applications in your Applications folder.
2. Drag it to the Trash, or select it and press Command-Delete.
3. Enter an administrator password when prompted.
4. Empty the Trash.
5. Go to the App Store and attempt to download the app again. This time it should work.

In the event that you still have an error, now also try:

• In the App Store, choose Store > Sign Out and then Store > Sign In.
• Restart your Mac via  > Restart.

This Mac 911 article is in response to a question submitted by Macworld reader Blain.

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