TendStartup guide
Mac keeps restarting: collect clues before changing everything
Investigate unexpected restarts by recording the trigger, testing peripherals and following Apple’s software and hardware checks.
Keep a short incident record
Write down the time, visible message, foreground task and connected devices. Note whether the restart happened during sleep, a call, a build or ordinary idle time. If possible, save important work and confirm that a recent backup is accessible.
An example record might say “Restarted while waking with one dock and external display attached; no restart yet without the dock.” Label that as an observation. One quiet session does not prove a repair.
Check software changes
Apple recommends available software updates and using safe mode to help isolate startup software. Review the affected app and plug-in vendors’ compatibility notes. Do not uninstall several unrelated tools at once: keep a record of one deliberate change and its result.
If the Mac cannot stay running long enough to save work, pause routine cleanup and contact Apple or a qualified service provider. Repeated interruptions make it harder to assess both the original problem and any changes you make.
Compare connected devices
Following Apple’s procedure, shut down and disconnect nonessential peripherals, leaving necessary input, display and power connections. Test for a period relevant to the usual symptom. If the problem stops, reconnect one device at a time and retest. A cable, dock or device path becomes a lead only when you can reproduce the difference.
Use Apple Diagnostics when appropriate
Apple Diagnostics can help assess internal hardware. Follow Apple’s instructions for your Mac and keep any reference code for support. A result should be interpreted alongside the symptom; neither a third-party health grade nor a missing warning certifies that every component is healthy.
Share a useful, private report
Send the Mac model, macOS version, incident times and the comparisons you performed. Logs may contain device identifiers, paths or application details, so avoid posting a full collection publicly. Tend Timeline can add observations recorded while it was running, but cannot reconstruct every earlier event or prove which event caused a restart.
Sources and further reading
Reviewed October 19, 2026 against the linked documentation. Menu names and capabilities vary by macOS version and device; these guides have not been physically tested on every supported Mac.