Reinstall macOS from Recovery and keep your files

Why it happens

When macOS itself is damaged, a fresh copy can fix crashes and odd behaviour that nothing else touches. Reinstalling from Recovery writes a new copy of macOS over the old one and doesn't erase your data. It downloads macOS, so you need a working internet connection.

How to fix it

1. Back up first. Open General > Time Machine and make sure a recent backup finished, or copy your important files to a drive.

   General›Time Machine

2. Plug a MacBook into power and keep the lid open the whole time.

3. On a Mac with Apple silicon, shut down, then press and hold the power button until you see Loading startup options. Click Options, then Continue. On an Intel Mac, press the power button and hold Command-R until the Apple logo appears.

4. If asked, pick your user and type your password. When the Recovery window appears, choose Reinstall macOS (it shows your version's name, such as macOS Tahoe on macOS 26) and click Continue.

5. Follow the prompts and choose your usual startup disk, normally Macintosh HD. The Mac restarts a few times on its own. When it's done you'll see your login window and your files.

Still not fixed?

1. If Recovery says it can't connect, pick your Wi-Fi network from the Wi-Fi menu at the top right of the Recovery screen and try again.

2. If the reinstall fails or the disk isn't offered, open Disk Utility from the Recovery window, select Macintosh HD and run First Aid, then try Reinstall macOS again.

3. Before reinstalling at all, it's worth checking General > Software Update. A normal update sometimes fixes the problem with less fuss.

   General›Software Update

4. If your Mac won't start up in Recovery, or Disk Utility can't see the internal disk, contact Apple Support or a repair shop. That can point to a hardware problem with the Mac's storage.