Mac keeps restarting? 7 things to check

2 min read · 7 steps · Updated 2 October 2026

Short answer

Install all macOS updates, then shut the Mac down and unplug every device except the display, keyboard and mouse. If the restarts stop, plug the devices back in one at a time to find the one at fault. If they continue, start in safe mode and run Apple Diagnostics.

After an unexpected restart, the Mac shows the message "Your computer was restarted because of a problem". Apple says the usual causes are software installed on the Mac or a device connected to it. A single restart is nothing to worry about. Repeated ones need the steps below.

Menu names are from recent versions of macOS, where the settings app is called System Settings.

Step by step

  1. Part of the Mac System Settings window: Install all updates

    Install all updates

    Open System Settings, click General, then Software Update, and install everything on offer. Update your apps as well.

  2. Remove an app that macOS names

    If the message after the restart names an app as the cause and offers Move to Trash, click it. Ask the maker of the app whether a newer version is available.

  3. Unplug everything

    Shut the Mac down. Disconnect drives, printers, hubs and all other devices. On a desktop Mac, leave only the display, keyboard and mouse or trackpad connected.

  4. Use the Mac as usual

    Switch the Mac on and use it for as long as it normally takes for a restart to happen. If it stays stable, a connected device is the cause.

  5. Reconnect devices one at a time

    Shut down, plug in one device, start the Mac and use it. Repeat with the next device until the restarts come back. The last device you added, or its cable, is the problem.

  6. Start in safe mode

    Safe mode loads only the essential parts of macOS. If the Mac is stable in safe mode, software that starts with the Mac is the likely cause. The steps are in how to start a Mac in safe mode.

  7. Run Apple Diagnostics

    With the devices still unplugged, run the built-in hardware test: how to run Apple Diagnostics on a Mac. Note any reference code it shows for Apple Support.

Good to know

If nothing helps, Apple's last software step is to reinstall macOS from macOS Recovery. This keeps your files, but make a backup first: how to back up a Mac with Time Machine.

A Mac that switches off when it gets hot or when the battery is low is a different fault. See Mac fan loud all the time: 6 things to check.

After a restart the Mac offers to send a report to Apple. Sending it is optional and does not fix the problem by itself.

In short: Update, remove the named app, unplug devices, test, reconnect one by one, safe mode, Apple Diagnostics.

Sources
  • Apple Support: If your Mac restarted because of a problem

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