Mac

Mac app can't be opened because it's from an unidentified developer

macOS blocks apps that aren't notarized by Apple as a security measure; if you trust the source, you can safely allow the specific app to open with a couple of clicks.

Difficulty
Easy
Time
5–10 minutes
DIY cost
$0
Pro cost
$0

Symptoms

  • Message says the app 'cannot be opened because it is from an unidentified developer'
  • Double-clicking the app does nothing but show this warning
  • The app was downloaded directly from a website rather than the App Store
  • Other apps open normally without this warning

Likely causes

  • CommonThe app isn't notarized or signed with an Apple Developer certificateThis is normal for many legitimate apps distributed outside the App Store.
  • CommonmacOS's Gatekeeper security feature blocking the app by defaultThis is intentional behavior, not necessarily a sign of a problem.
  • PossibleThe app was downloaded from an untrusted or unofficial sourceIn this case, the warning may be pointing to a real risk worth taking seriously.
  • CommonA quarantine flag automatically applied to files downloaded from the internetmacOS tags downloaded files this way regardless of the app's legitimacy.
  • PossibleAn older version of the app not updated for current macOS security requirementsSome abandoned or outdated apps trigger this more readily.

What to do

  1. Confirm the app came from a source you trust (the developer's official website, not a random download site) before proceeding.
  2. Right-click (or Control-click) the app icon and choose Open instead of double-clicking.
  3. Click Open in the dialog that appears, which only needs to be done once for that specific app.
  4. If that doesn't show an Open option, go to System Settings > Privacy & Security and look for a message about the blocked app, then click 'Open Anyway.'
  5. Enter your Mac's password or use Touch ID to confirm you want to allow the app.
  6. The app should now open normally in the future without repeating this warning.
  7. If you're unsure about the app's legitimacy, don't override the warning and instead look for the app on the App Store or verify the developer's official site.
  8. For repeated or many similar warnings, check that you're downloading software from official sources going forward.

Tools and parts

  • None required

When to call a pro

This is a simple security setting; professional help isn't needed unless you suspect the app itself is malicious, in which case don't open it at all.

Safety

Generally low risk

Generally low risk for a careful person. Stop if anything looks different from what this guide describes.

Related guides

Operator provides AI-generated troubleshooting information. It can be wrong. For safety-critical, electrical, gas, structural, medical, automotive safety, or other high-risk problems, consult a qualified professional.