Install an app you downloaded from a website

Why it happens

Apps from the App Store install themselves, but apps from a developer's website arrive as a file you have to open. A .dmg is a small virtual disk that holds the app, and a .pkg is an installer that walks you through the setup. Until you copy the app into Applications, it isn't really installed.

How to fix it

1. Download the app from the developer's own website. In Finder, open Downloads from the sidebar and find the file you just got.

   Finder›Downloads

2. For a .dmg, double-click it. Your Mac checks it for a few seconds, then a window opens showing the app, often with an arrow pointing to an Applications folder.

3. Drag the app's icon onto that Applications folder and wait for the copy to finish. If there's no Applications folder in the window, open a new Finder window and drag the app to Applications in the sidebar instead.

4. Eject the disk: click the eject button next to its name in the Finder sidebar. You can then move the .dmg file to the Trash, since the app now lives in Applications.

5. For a .pkg, double-click it and click Continue through each screen. Enter your Mac password when asked, which is normal for installers.

6. Open the new app from your Applications folder. The first time, your Mac asks if you really want to open an app downloaded from the internet. Click Open if you trust where it came from.

Still not fixed?

1. If the app vanishes or asks to be installed again each time, you were probably opening it straight from the .dmg window. Drag it into Applications, eject the disk, and open it from Applications from then on.

2. If the .dmg won't open or says no mountable file systems, the download was probably cut short. Move it to the Trash, download it again, and let the check finish before you do anything else.

3. If your Mac says it can't check the app for malicious software, only go further for an app you trust from a known developer. Try to open it once, then go to Privacy & Security, scroll to Security, and click Open Anyway next to the app's name. Enter your password to confirm.

   Privacy & Security›Security›Open Anyway

4. If your Mac says the app is damaged, don't try to force it open. Delete it and download a fresh copy from the developer's official site, because a damaged file can't be trusted.

5. If one app still won't install, contact its developer, since they know their installer best. If no app from the web installs at all, contact Apple Support.