Error 'Cannot Verify Developer' in macOS: How to Fix

What the "Cannot Verify Developer" Error Means

The "Cannot Verify Developer" error appears in macOS when the Gatekeeper system blocks an app that is either unsigned by an Apple certificate or has a damaged signature. This typically happens after downloading software from the internet (not from the App Store).

The system displays a dialog with the text:

"App Name" cannot be opened because Apple cannot verify it is free from malware.

This is a protective mechanism, but it can sometimes block safe applications from independent developers.

Common Causes

1. App is not signed by an Apple-certified developer
   The developer has not paid for the Apple Developer Program ($99/year) or has not added the app to their account. Gatekeeper considers such apps untrusted.
2. Corrupted app signature or file
   The file may have been partially damaged during download (e.g., due to a network issue), breaking the digital signature.
3. Strict Gatekeeper settings
   In System Settings → Security & Privacy, the setting is configured to App Store instead of App Store and identified developers. This blocks all apps outside the App Store.
4. Outdated macOS version
   On older systems (pre-macOS Catalina), Gatekeeper is less precise but may still erroneously block apps signed with newer certificates.
5. Antivirus or firewall
   Some third-party security tools (e.g., Little Snitch, antivirus software) may perform additional signature checks and block apps.

Solutions

Solution 1: Allow via Security Settings (Recommended)

This is the safest method—macOS remembers the permission for that specific app.

1. Try launching the app by double-clicking it. If the error appears, do not click "OK"—just close the window.
2. Open System Settings → Security & Privacy.
3. In the General section, you'll see a message like:
   "App Name" was blocked from use because it is not from an identified developer.
4. Click the "Open Anyway" button.

   ⚠️ If the button is grayed out, unlock the settings by clicking the lock icon at the bottom and entering an administrator password.

5. Confirm the action in the dialog that appears.
6. Now try launching the app again—it should open.

Note: Gatekeeper will remember this permission. If the app is updated, you may need to grant permission again.

Solution 2: Use Terminal (spctl)

If Solution 1 doesn't work (e.g., the "Open Anyway" button is missing), use the command line.

1. Open Terminal (via Spotlight Cmd+Space or in Applications → Utilities).
2. Enter the command, replacing [path/to/app.app] with the actual path:

   sudo spctl --add --label "Whitelist" "[path/to/app.app]"
   

   Example for an app on the Desktop:

   sudo spctl --add --label "Whitelist" ~/Desktop/MyApp.app
   

3. Enter your administrator password (characters won't be displayed—this is normal).
4. Now try launching the app.

Alternative command (temporarily disables Gatekeeper for all apps—not recommended):

sudo spctl --master-disable

This will add an "Anywhere" option in Security settings. To restore default settings:

sudo spctl --master-enable

Solution 3: Install via Homebrew (for CLI Tools)

If the app is a command-line tool (e.g., ffmpeg, node), use the Homebrew package manager. It handles signatures automatically.

1. Install Homebrew (if not installed):

   /bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"
   

2. Install the app:

   brew install app_name
   

   Example: brew install wget.

Homebrew downloads packages from verified repositories, so Gatekeeper won't block them.

Solution 4: Verify App Integrity

If the app is corrupted, Gatekeeper may mistakenly flag it as untrusted.

1. Check the hash (SHA-256) of the downloaded file. The developer usually publishes this on their website.

   shasum -a 256 ~/Downloads/MyApp.dmg
   

2. Compare the output with the expected hash. If they don't match, redownload the file.
3. For apps in .dmg or .zip format, repackage them:
   • Mount the .dmg image, copy the .app to the Applications folder.
   • Delete the original archive and restart your Mac.

Prevention

• Download apps only from official websites or the App Store. Avoid torrents and questionable repositories.
• Check developer signatures. In Finder, select the app → File → Open (or Cmd+Space and type "Open"). macOS will show developer information.
• Don't disable Gatekeeper entirely. If needed, use temporary permissions (Solution 1) or a whitelist via Terminal (Solution 2).
• Keep macOS updated. Newer versions improve signature verification and reduce false positives.
• For CLI tools, use Homebrew or official installers (.pkg), which often have proper signatures.

💡 Tip: If you are a developer and want to distribute your apps without errors, enroll in the Apple Developer Program and sign your builds via Xcode (Product → Archive → Distribute).

Common Issues & Fixes

Issue: After clicking "Open Anyway," the app still won't launch.
Fix: Restart your Mac. Sometimes Gatekeeper applies changes only after a reboot.

Issue: An App Store app also shows the error.
Fix: Update macOS to the latest version. If the problem persists, it may be a corrupted App Store cache—run sudo rm -rf /private/var/folders/* (carefully!) or reinstall the app.

Issue: The spctl command returns "source=Notarized Developer ID".
Fix: This is normal—the app is signed but not notarized by Apple. Notarization is required for macOS Catalina and later. If the developer hasn't notarized the app, use Solution 1 or 4.

Issue: Need to run the app on a remote Mac via SSH.
Fix: Gatekeeper only works in the graphical environment. Launch the app locally via VNC, or use sudo spctl --add remotely (requires admin privileges).