How-toMac

Install apps on a Mac and fix "can't be opened" warnings

Install apps from the App Store or the web, remove them cleanly, and handle macOS warnings such as "cannot be opened because the developer cannot be verified".

  • Updated
  • 10 min
  • Beginner
Applies to
  • Mac

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Mac apps come from the App Store or from a maker's website. Install both kinds safely, remove an app, and learn what a macOS security warning means before you decide to override it.

Where apps should come from

Apps on the App Store go through Apple's app review. Apps from outside the store are checked by macOS differently: it looks for the developer's signature and, by default in macOS Catalina and later, for notarization (a check Apple runs on the developer's software). That check is what produces the warnings you may see.

Where to get a Mac app3 numbered steps, one under the other. The full text follows the picture.Where to get a Mac app1App StoreApps go through Apple's appreview2Maker's websiteUse only the official site youtrust3Never a pop-upDo not install what a pop-upor caller offers
Choose the first option that has the app.
Text version of this diagram
  1. App Store: Apps go through Apple's app review
  2. Maker's website: Use only the official site you trust
  3. Never a pop-up: Do not install what a pop-up or caller offers

Official sources only

Use the App Store, or the developer's own website that you typed or found yourself. Never install an app because a pop-up, an email or a caller told you to. See safe downloads and fake driver sites.

Install an app

From the App Store

  1. Open App Store from the Dock or the Applications folder.
  2. Search for the app, check the developer's name, and click the price or Get button.
  3. Sign in with your Apple Account if asked. The app downloads and appears in the Applications folder.

From a website

  1. Download the file from the developer's official website. It usually ends in .dmg (a disk image) or .pkg (an installer package).
  2. Open the Downloads folder and double-click the file.
  3. If a window opens showing the app and an Applications folder, drag the app onto the Applications folder. This is the usual layout for disk images, but each developer's window can look a little different.
  4. If an installer opens instead, follow its on-screen instructions.
  5. When the install finishes, eject the disk image in Finder and move the downloaded file to the Trash.

For what the file types mean, see EXE, MSI, DMG, PKG and APK files explained.

Installing from a disk image3 numbered steps, one under the other. The full text follows the picture.Installing from a disk image1DownloadFrom the official site only2Open the .dmgDouble-click it in Downloads3Drag to ApplicationsThen eject the disk image
The most common layout for downloaded Mac apps.
Text version of this diagram
  1. Download: From the official site only
  2. Open the .dmg: Double-click it in Downloads
  3. Drag to Applications: Then eject the disk image

Fix "can't be opened" warnings

Apple lists several warnings. Read the exact wording, because it tells you what to do.

Common macOS app warnings
WarningWhat Apple says to do
Developer cannot be verified, or Apple cannot check it for malicious softwareLook for an updated or alternative app on the App Store. Override only if you are certain the source is trustworthy.
Not downloaded from the App StoreYour setting allows only App Store apps. Override for this app or change the setting.
App is damaged, or will damage your computerThe app may be corrupted or tampered with. Do not force it open. macOS may move known malware to the Trash.

Think before you override

Apple warns that running software that is not signed and notarized may expose your computer and personal information to malware. Only continue if you are certain the app is trustworthy and unaltered. If a caller, email or pop-up told you to install it, stop and do not open it.

Open an app that macOS blocked

  1. Try to open the app once. The warning appears, and this makes the next option available.
  2. Choose Apple menu then System Settings then Privacy & Security.
  3. Scroll down to the Security section and click Open Anyway.
  4. Click Open when the warning appears again, and type your login password if asked.

The app is then saved as an exception, so you can open it by double-clicking later. On macOS Sequoia (15) and later this is Apple's method. Older guides describe a Control-click shortcut that some earlier versions used.

Check which apps your Mac allows

In System Settings then Privacy & Security, scroll to Security. Under Allow apps downloaded from you can choose App Store or App Store and identified developers. This setting may be locked if an employer or school manages your Mac.

Remove an app

  1. Click the Finder icon in the Dock, then click Applications in the sidebar.
  2. If the app is inside a folder, look in that folder for an Uninstaller. If there is one, run it and follow the prompts.
  3. Otherwise, drag the app to the Trash.

Emptying the Trash is permanent

The app is removed for good the next time the Trash is emptied. To keep it, select it in the Trash and choose File then Put Back first. Some built-in apps that macOS protects cannot be removed. Removing an app does not delete your own documents, but check you do not need data stored inside it.

If something goes wrong

  • If you think you installed something harmful, see how to run a malware scan.
  • If the Mac says an app is in use when you try to remove it, quit the app, or restart the Mac, then try again.
  • If a Mac app is frozen, see force quit and recover.

Frequently asked questions

Is an app from the App Store always safe?

It is reviewed and signed by Apple, which lowers the risk, but you should still check the developer name and read what the app asks permission for.

Why does a trusted app show a warning?

The developer may not have signed or notarized it, or an old copy may have been damaged. Look for a newer version on the developer's official site first.

Does dragging an app to the Trash remove everything?

It removes the app. Small settings files may remain, which is normally harmless. If the app came with an Uninstaller, use that instead.

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Official resources used

Pages consulted while preparing this guide. Check them for the latest details.

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