The cause of messages like this can vary. If the message recommends a solution, such as to redownload the installer and try again, please do that first. The other solutions here are organized starting with the easiest. If the issue persists, or you need help with these instructions, please contact Apple Support.
Install in safe mode
Install while your Mac is started up in safe mode. To start up in safe mode, determine whether you're using a Mac with Apple silicon, then follow the appropriate steps:
- Shut down your Mac.
- Turn on your Mac and continue to press and hold the power button until you see the startup options window.
- Select your startup disk, then press and hold the Shift key while clicking “Continue in Safe Mode.”
- Log in to your Mac. You might be asked to log in again.
- Turn on or restart your Mac, then immediately press and hold the Shift key as your Mac starts up.
- Release the key when you see the login window, then log in to your Mac.
- You might be asked to log in again. On either the first or second login window, you should see ”Safe Boot” in the upper-right corner of the window.
Install after repairing your disk
Install after using Disk Utility to repair your startup disk.
Install from macOS Recovery
Install while your Mac is started up from macOS Recovery. This gives you the latest version of the macOS currently or most recently installed. To start up from macOS Recovery, follow the appropriate steps:
Turn on your Mac and continue to press and hold the power button until you see the startup options window. Click the gear icon labeled Options, then click Continue.
Turn on your Mac and immediately press and hold Command (⌘)-R until you see an Apple logo or other image.
If you're asked to select a user you know the password for, select the user, click Next, then enter their administrator password. When you see the utilities window in macOS Recovery, select Reinstall macOS, then click Continue and follow the onscreen instructions. Learn more about using macOS Recovery to reinstall.