Troubleshooting

Explains how to force an unresponsive app to close, after trying a normal quit first, and what to do if that fails.

Covers what to do when an app stops responding or closes by itself: force quit, restart, check compatibility and updates, and remove recent add-ons.

Lists common reasons for a sluggish Mac, such as a nearly full disk or memory-hungry apps, and checks to try including Activity Monitor and Disk Utility.

Explains that a flashing question mark means the Mac cannot find a working startup disk. Walks through repairing the disk in Recovery, reinstalling macOS and checking Startup Disk settings and NVRAM.

Lists which keys or buttons to hold at startup to reach tools like Recovery, startup disk selection and diagnostics, with separate sections for Apple silicon and Intel Macs.

Explains how to start in safe mode to see whether startup software is causing a problem, with separate methods for Apple silicon and Intel Macs, and how to confirm it worked.

Describes how to run Apple Diagnostics to help pinpoint which hardware component may be causing a problem, and how to read the reference codes.