My iMac desktop computer frequently restarts with an error message "Your Computer was restarted because of a problem".

Check your software

If the issue is caused by software on your Mac, one of these steps might help:

• Install all available software updates.
• If your Mac suspects that a particular app caused the restart, it might ask whether you would like to move the app to the Trash. Click Move to Bin, then contact the software developer to see if a software update is available.
• Use safe mode to try to isolate the cause of the issue.
• Reinstall macOS. If the issue continues after reinstalling macOS, check your hardware.

Check your hardware

Learn how to check your connected devices and other hardware.

Check peripheral devices first

If you don't have any devices attached to your Mac, skip to the next section.

1. Shut down your Mac.
2. Disconnect all peripheral devices, such as hard drives or printers. If you have a desktop Mac, make sure that only a display, keyboard, mouse, or trackpad are connected.
3. Turn on your Mac.
4. Use your Mac for the amount of time that it would usually take for an unexpected restart to occur.
5. If an unexpected restart occurs, follow the steps to check the internal RAM and third-party hardware.
6. If an unexpected restart doesn't occur, turn off the Mac and connect one peripheral device at a time until an unexpected restart occurs.

About unexpected restarts

Rarely, your Mac might experience a software or hardware issue that requires it to restart. When it starts up again, you might see a message that your computer was restarted because of a problem.

Unexpected restarts are usually caused by software installed on your Mac, or by devices connected to your Mac. If the issue causes your Mac to restart every time it attempts to start up, your Mac might eventually shut down. Use the steps below to check the software and hardware on your Mac.

If your Mac restarted because of a problem – Apple Support (AU)