University of Oregon

Mac OS X Startup Sequence & Error Codes and Symbols



The following is an overview of the startup sequence, error conditions, and behaviors for all Intel-based Macintosh systems.

For any other issues besides these errors and symbols, and you're still having problems starting up your Mac, please refer to

Error/Symbols on Start-up

Startup Sequence stage Event
Power On Boot-ROM/RAM check is initialized
  • Black screen, power LED on: POST or BootROM failure
  • Flashing power LED once per second: bad RAM or no RAM
  • Three flashes, a pause, and three more flashes (occurs continuously): marginal RAM
BootROM-EFI Boot chime
Boot EFI
  • Metallic Apple: found boot.efi
  • Circle with slash: could not load boot.efi, or some other issue
  • Flashing globe: looking on the network for booter/kernel on netboot server
  • Metallic Apple with spinning earth below: found booter/kernel on netboot server
  • Broken Folder that blinks: no bootable device or operating system was found
kernel Grey screen with Metallic Apple and spinning gear
launchd Blue screen
loginwindow Login window appears
User Environment Setup The text "Logging in..." appears in login window along with a progress bar. Upon successful login, the Desktop and Dock appear.