Mac App Store: "An unknown error occurred (100)" when purchasing

Products Affected

Mac App Store

Symptoms

When attempting to purchase an app, an alert may appear indicating the app couldn't be purchased, as well as "An unknown error occurred (100)".

Resolution

Try the following steps to workaround this issue:

  1. Quit App Store.
  2. Wait 10 seconds or more.
  3. Open App Store again.
  4. Navigate to the desired app.
  5. Click Buy.

If the issue persists, try restarting your computer and attempting the app purchase again.

Additional Information

  • For other solutions to App Store issues, see Troubleshooting the Mac App Store
  • You can find additional information by choosing Help > App Store Help from within the application.
  • Additional articles and support resources for Mac App Store are available here.
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