Security & accounts

Mac won't open an app, says it's from an unidentified developer

macOS blocking an app as being from an 'unidentified developer' is a built-in safety check, not necessarily a sign the app is dangerous. Verifying the app's source before overriding the warning keeps you protected.

Difficulty
Easy
Time
5–15 minutes
DIY cost
$0

Symptoms

  • Message saying the app can't be opened because it's from an unidentified developer
  • App downloaded outside the Mac App Store
  • Option to open it anyway hidden in settings
  • App worked fine before a macOS update

Likely causes

  • CommonApp isn't notarized or signed by ApplemacOS flags apps that haven't gone through Apple's verification process, which is common for many legitimate smaller developers too.
  • PossibleDownloaded from an untrusted or unofficial sourceIf the app came from a site other than the developer's official page, it could be a modified or unsafe version.
  • Less commonGenuinely malicious softwareIn rare cases the warning is correctly flagging harmful software.

What to do

  1. Confirm the app came from the developer's official website or a source you trust, not a random download link.
  2. If you're confident it's legitimate, go to System Settings > Privacy & Security and look for an 'Open Anyway' option after the first blocked attempt.
  3. Alternatively, right-click (or Control-click) the app and choose Open, then confirm in the dialog that appears.
  4. If you're not sure of the app's legitimacy, don't override the warning; delete the file instead.
  5. Run a malware scan on the downloaded file before opening it if there's any doubt.
  6. Check online reviews or the developer's reputation if you're unfamiliar with the software.
  7. Only download software going forward from official sources or the Mac App Store when possible.

When to call a pro

If you're unsure whether an app is safe and it's important for work, ask a knowledgeable colleague or IT professional to verify it before opening.

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.