- Folder with a question markHold Option at startup to pick a disk. If none appears, the drive has failed or its connection has, and on newer machines that means the logic board.
- No startup disk was found — the Mac looked for a bootable system and did not find one.
- Prohibitory sign (circle with a line)Usually a macOS version too old for the hardware, or a wrong-architecture installer. Reinstall the version the machine shipped with or later.
- A startup disk was found but its system cannot run on this Mac.
- Grey or black screen, no chimeRules out software almost entirely. Disconnect every peripheral, then reset NVRAM and the SMC on Intel machines. On Apple silicon, hold the power button for ten seconds.
- The Mac is not reaching the point of drawing anything.
- Apple logo, progress bar stallsLeave it — a stalled bar after an update can genuinely take an hour. If it does not move, boot into Recovery and run First Aid on the disk.
- The system is loading but not completing.
- Circle with a slash on Apple siliconReinstall macOS from Recovery. This appears after a failed update or an interrupted installation.
- The system on the disk is not signed or has been altered.
- Globe with alertWired Ethernet or a different network. Captive-portal Wi-Fi does not work for Internet Recovery.
- Internet Recovery could not reach Apple's servers.
- Login window loopsUsually a corrupt preference or a login item. Boot into safe mode by holding Shift, which skips login items.
- The system boots but cannot complete login.
- Padlock with a passcode fieldOnly Apple can remove it, and only with proof of purchase. It is not resettable by any tool.
- A firmware password is set.