Panic: no external boot disk

THE INTRODUCTION OF completely novel hardware inevitably brings the unexpected when some people among the millions of new users do things that the engineers hadn’t anticipated. One failing in M1 Macs is the common situation in which an external startup disk is removed when that Mac is shut down.

If that disk was selected as the startup disk and is nowhere to be found when the Mac next boots, the result is total catastrophe; it panics, causing another boot, which leads to another panic, and so on until you force it to shut down, then start it up in Recovery.

It shouldn’t be hard for the firmware to cope with this by entering Recovery in the first place and letting you choose an available startup disk, but Apple still hasn’t fixed this in the eight months since it started delivering these new Macs to users.