Damaged App Cannot Be Opened on macOS: Fixes

If you see ““App” is damaged and can’t be opened” on macOS, it usually means Gatekeeper has quarantined the app because its signature or origin doesn’t match Apple’s security expectations. The fix is to remove the quarantine attribute with a Terminal command, or to right-click and open the app manually if it was downloaded from the internet. Below are the exact steps, why this happens, and how to avoid it in the future.

What Causes the “Damaged” Error

macOS uses a security feature called Gatekeeper, which checks every app you download from the internet against Apple’s notarization service. If an app is not notarized (or was modified after download), macOS adds a quarantine flag to the file. When you try to open it, the system displays ““App” is damaged and can’t be opened. You should move it to the Trash.” This message is misleading—the app is rarely actually damaged. It simply lacks the expected digital signature or has been flagged because it was downloaded from an unidentified developer.

How to Fix It: Remove the Quarantine Attribute

The most reliable fix is to remove the quarantine attribute using Terminal. This tells macOS that you trust the app and want to open it anyway.

Open Terminal (found in Applications > Utilities).
Type xattr -dr com.apple.quarantine followed by a space.
Drag the app icon from Finder into the Terminal window. The path will appear automatically.
Press Return. If successful, you’ll see no output.
Try opening the app again. It should launch normally.

If you still get the error, try the alternative: right-click (or Control-click) the app in Finder and select Open. This often works for apps that are only blocked by Gatekeeper, not truly damaged. If that fails, check if the app is actually corrupted by downloading it again from the official source.

Why Right-Clicking Sometimes Works

When you right-click an app and choose Open, macOS shows a dialog with an Open button instead of the usual warning. This bypasses the quarantine check for that one launch. However, if the app’s signature is completely invalid (e.g., it was tampered with), right-clicking won’t help. In that case, the quarantine attribute removal is the more thorough solution because it clears the flag entirely.

Other Common Causes and Fixes

App is from an unidentified developer: Go to System Settings > Privacy & Security, scroll down, and you’ll see a message about the blocked app. Click Open Anyway.
App is 32-bit: macOS Catalina and later do not support 32-bit apps. The error will say “You can’t open this application because it is not supported on this Mac.” There is no fix other than finding a 64-bit version.
App is damaged during download: Re-download the file from the developer’s website. A corrupted download can trigger the same message.
App is from an unknown source: If you’re sure the app is safe, you can temporarily disable Gatekeeper by running sudo spctl --master-disable in Terminal, but this lowers security and is not recommended for long-term use.

How to Prevent the Error in the Future

To avoid this issue, always download apps from the Mac App Store or from the developer’s official website. Developers can notarize their apps with Apple, which automatically clears the quarantine flag for all users. If you frequently download open-source or beta apps, you’ll likely see this error more often. In that case, you can keep a Terminal command ready to remove the quarantine attribute as a habit. Also, check the app’s documentation—many developers include a note about the “damaged” error and provide the exact fix.

Is It Safe to Remove the Quarantine Attribute?

Removing the quarantine attribute is generally safe if you trust the app and its source. The quarantine flag is only a marker that tells macOS to check the app’s notarization status. By removing it, you’re telling macOS to skip that check. However, if the app is actually malicious, you’re bypassing a security layer. Only do this for apps you’ve downloaded from a reputable developer. If you’re unsure, run a malware scan with a trusted security tool before opening it.

Frequently Asked Questions

Why does my Mac say an app is damaged when it worked before?

This can happen after a macOS update that changes security policies, or if the app’s signature expired. Re-downloading the app or removing the quarantine attribute usually fixes it.

Can I open a damaged app without Terminal?

Yes, try right-clicking the app and selecting Open. If that doesn’t work, go to System Settings > Privacy & Security and look for the app under the security section. You may see an Open Anyway button.

What if the app is from the Mac App Store but shows this error?

This is rare. Try deleting the app and re-downloading it from the App Store. If the problem persists, restart your Mac and try again. If it still fails, the app may have a bug that requires the developer to update it.

Does this error mean my Mac is infected?

No. The error is a security warning, not an infection indicator. It simply means the app hasn’t passed Apple’s notarization check. However, if you downloaded the app from an untrusted source, it could be risky, so be cautious.

Will removing the quarantine attribute void my warranty?

No. This is a standard troubleshooting step and does not affect your hardware warranty or macOS system integrity.

General steps for current mainstream versions; menus can differ by device and version. See the disclaimer or report an error.

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