MacMP
Common System Updated 2026-09-26

"Cannot Be Opened Because Apple Cannot Check It" — How to Fix It Safely

“A downloaded app will not open because the developer cannot be verified”

This is Gatekeeper blocking an unnotarized app, not a broken download. Right-click to open it first; only use the terminal workaround on software you actually trust.

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⚡ Try this first

Right-click the app in Finder, choose Open, then click Open again in the dialog. This is the safest method.

What you are seeing

  • "Cannot be opened because the developer cannot be verified"
  • The app is reported as damaged and should be moved to the Trash
  • Right-clicking does not offer an Open option
  • The app installs and then immediately quits

Common causes

  • The app has not been notarized by Apple
  • It came from outside the App Store
  • A quarantine attribute is blocking execution
  • Architecture mismatch on Apple silicon

Full walkthrough

  1. 01

    Use right-click to open

    Find the app in Finder, right-click (or Control-click) it and choose Open. The dialog now includes an Open button. Clicking it remembers your choice, and double-clicking works from then on.

  2. 02

    Allow it in Privacy settings

    If right-click is still blocked, open System Settings → Privacy & Security and scroll down. You will see a message that an app was blocked, with an Open Anyway button. Click it and authenticate.

  3. 03

    Remove the quarantine attribute

    If macOS claims the app is damaged, it usually means a quarantine flag was attached during download. Removing the flag normally lets it run.

    Terminal 
    sudo xattr -rd com.apple.quarantine /Applications/YourApp.app
    ⚠️ Heads upThis bypasses a system security check. Only use it on software whose source you genuinely trust, never on files from unknown download sites.
  4. 04

    Check the app architecture

    Apple silicon Macs need Rosetta 2 for Intel-only binaries. If an app quits immediately on launch, check its architecture and install Rosetta if required.

    Terminal 
    file /Applications/YourApp.app/Contents/MacOS/*
  5. 05

    Re-download from the official source

    If nothing works, download it again from the developer’s site. Avoid third-party download portals and "cracked" builds — they are a security risk and frequently fail verification because the binary was modified.

    ⚠️ Heads upDo not disable Gatekeeper globally to work around this. It significantly weakens the security of your Mac.

How to prevent it

  • Get software from official sites or the App Store
  • Re-check compatibility of essential apps after a system update
  • Never globally disable Gatekeeper or SIP

Follow-up questions

Is the app actually damaged?

Usually not. It is almost always the quarantine attribute applied at download time. Removing it with xattr typically restores normal operation.

Can I permanently turn off Gatekeeper?

Technically yes, but it is not advisable. Gatekeeper is a primary line of defence, and disabling it makes malware attacks considerably easier.

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