The Cluttered Login
When you restart your Mac (or install a system update that requires a reboot), macOS includes a “resume” feature designed to seamlessly bridge your sessions. By default, as soon as you log back in, the operating system will attempt to automatically relaunch every single application and reopen every single window that was active the moment you clicked “Restart.” While this sounds convenient in theory, in practice, if your Mac crashed due to memory pressure from having 50 Safari tabs open, automatically reopening those same 50 tabs on boot will simply cause the machine to immediately freeze again.
Starting with a Clean Slate
To ensure a fresh boot and stop macOS from automatically reopening your previous windows and applications on restart, you must uncheck a specific box during the shutdown sequence.
This setting is not permanently buried in System Settings; it is presented to you every time you shut down. Click the Apple logo in the top-left corner and select Restart… or Shut Down…. A small confirmation dialogue box will appear in the center of your screen, counting down from 60 seconds. Directly above the “Restart” and “Cancel” buttons, you will see a checkbox labelled Reopen windows when logging back in. If this box is checked, your Mac will attempt the resume feature. Simply click the checkbox to remove the checkmark before you click the Restart button. When your Mac boots back up, it will present a completely clean, empty desktop.