When you download a software application from a website instead of the official Mac App Store, macOS applies an invisible, sticky security tag to the file called the “Quarantine Flag.” Before the app is allowed to run, macOS checks this flag against a list of Apple-approved developers (a system known as Gatekeeper).
If the developer hasn’t paid Apple’s annual developer fee, or if the software is a niche open-source tool, Gatekeeper will instantly block the app. macOS will throw a terrifying error message stating: “[App Name] is damaged and can’t be opened. You should move it to the Trash.” The app is almost certainly not damaged; macOS is simply lying to enforce its security protocol. You can safely bypass this check by stripping the quarantine flag off the file.
How to Safely Bypass the Mac ‘App is Damaged’ Error
You must use the xattr (Extended Attributes) command in the Terminal to delete the quarantine flag.
Warning: Only perform this bypass if you absolutely trust the website where you downloaded the software.
- Ensure the “damaged” app is located in your Applications folder (not sitting in your Downloads folder or on a mounted `.dmg` disk image).
- Open the Finder, go to Applications, open the Utilities folder, and double-click Terminal.
- In the Terminal window, carefully type the following exact command, ensuring you leave a single space at the very end. Do not press Enter yet.
sudo xattr -cr - Now, open a Finder window and locate the application that refuses to open.
- Click and drag the application icon directly from the Finder window into the Terminal window.
- When you let go of the mouse button, the Terminal will automatically type the exact file path (e.g.,
sudo xattr -cr /Applications/BlockedApp.app). - Press Enter in the Terminal window.
- Because you are bypassing a core system security layer, the Terminal will ask for your Mac login password. Type it in (the characters will remain invisible) and press Enter again.
The Terminal will not output any confirmation message, but the fix is instantaneous. The invisible quarantine flag has been violently stripped from the file’s metadata. You can now double-click the application in your Finder, and it will open immediately, flawlessly bypassing the “damaged” error.