When macOS says “App” is damaged and can’t be opened. You should move it to the Trash, the app usually isn’t physically damaged. Gatekeeper, the part of macOS that checks apps you download, couldn’t validate the app’s code signature. That can mean a broken download, a modified app, or an app the developer never signed properly. Here’s how to tell which, and how to fix it without switching off your Mac’s protection.
Read the message first: they mean different things
| Message | What it usually means | What to do |
|---|---|---|
| “…is damaged and can’t be opened” | The code signature is missing, broken or doesn’t match the app’s files. Often an incomplete download, a modified app, or an unsigned app from the internet. | Follow the steps below, starting with a fresh download. |
| “Apple could not verify… is free of malware” (older: “can’t be opened because Apple cannot check it”) | The app is signed but wasn’t notarized by Apple. | Only open it if you trust the source; see Open Anyway below. |
| “…can’t be opened because it is from an unidentified developer” | The app isn’t signed with an Apple Developer ID. | Same as above. |
| “…will damage your computer” | macOS’s built-in malware protection recognized it. | Move it to the Trash. Don’t bypass this one. |
1. Download it again from the developer
A download that stopped partway, or a copy from a mirror or file-sharing site, is the most common cause. Delete the app, empty the Trash, and download it again from the developer’s own website or GitHub Releases page. If you copied the app from another Mac or a backup, download a fresh copy instead.
2. Check the signature yourself
Two Terminal commands tell you what macOS sees (swap in your app’s name):
codesign --verify --deep --strict --verbose=2 /Applications/App.app
spctl -a -vv /Applications/App.appA healthy app passes the first command and shows accepted with source=Notarized Developer ID or source=Mac App Store for the second. Messages such as invalid signature, a sealed resource is missing or invalid or code object is not signed at all confirm the signature is the problem. Our guide to checking whether a Mac app is signed and notarized explains every line.
3. Update to the latest version
An old version may have been signed with a certificate the developer has since replaced, or may not support your version of macOS. The developer’s current download fixes both.
4. If you trust the app: Open Anyway
Some legitimate apps, often small open-source projects, aren’t notarized because the developer doesn’t pay for an Apple Developer account. If you trust the source:
- Try to open the app once and close the warning.
- Open System Settings → Privacy & Security and scroll to Security.
- Click Open Anyway next to the app’s name, then confirm with your password.
Since macOS Sequoia, Control-clicking an app and choosing Open no longer skips this check, so System Settings is the only route (AppleInsider’s write-up). The button only appears for a while after you try to open the app. You only need to do this once per app. Apple’s overview: Safely open apps on your Mac.
5. Last resort: clear the quarantine flag on that one app
If Open Anyway doesn’t appear and you are certain the app is genuine, you can remove the “downloaded from the internet” flag from that app only:
xattr -dr com.apple.quarantine /Applications/App.appThis tells macOS to skip the first-launch check for that app. It doesn’t repair anything, so only use it for software you trust.
What not to do
- Don’t turn Gatekeeper off with
sudo spctl --master-disable. That removes the check for every app you open from then on, not just the one you’re fixing. - Don’t bypass a “will damage your computer” warning. That one means macOS recognized malware.
- Don’t download “fixed” copies from anywhere other than the developer.
When it happens right after an update
If an app opened fine yesterday and is “damaged” after updating, the update was probably interrupted or replaced only part of the app. Download the full app again from the developer. This is the failure that update checks are designed to prevent: Current verifies the developer, notarization and compatibility of a new version before it touches the installed app, keeps the previous copy aside, and puts it back if the new one fails its final check.
FAQ
Is my Mac infected if an app says it’s damaged?
Usually not. “Damaged” means macOS couldn’t validate the signature, which is most often a download problem. The warning that points to malware is “will damage your computer.”
Will reinstalling the app delete my settings?
Generally no. Most apps keep settings in your Library folder, not inside the app, so replacing the app keeps them.