Mac not working - white circle and bar?

Weird thing with our Mac - after entering the user password, it comes up with a black screen with a white circle and bar (like the red symbol for “no” only white.

Anyone have any idea why?

According to Apple support, it’s a problem with MacOS

If you scroll down here, there are some suggestions on a fix
https://discussions.apple.com/thread/8297759 (No clue how useful they are though)

Yeah, that’s bad.
That means the machine got a kernel panic early in the boot process. You need to re-install the OS from the recovery partition.

Thank you.

All I really understand is “that’s bad”

Off to the Mac shop we go for the repairs. :frowning:

basically the Mac version of a Blue Screen of Death.

Mac guy said that it needs to be re-loaded with OS, plus there may be some physical damage …
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I back up my Mac to an external drive using Time Machine. In the event this ever happens to me, can I boot from the external drive? (If so, how?)

A Time Machine backup is not bootable. It’s a pile of incremental backups that get re-assembled when restoring to a fresh drive. I use Time Machine for long term backups (“pretty sure I had the file I need four months ago” type stuff), but for emergency bootable backups, I have Carbon Copy Cloner make a complete, bootable backup to an external drive every evening.

And since fire or theft or earthquake could wipe out both backups at the same time, I make sure that everything that would be hard to recover (not apps, not the system) in the cloud as well.

You can’t boot from it, but you can use the Recovery Partition (boot with the cmd-R keys held down) to restore from it.

I had no idea such a thing existed.

It’s pretty handy.
It will even allow you to re-install from the Internet (direct download from Apple’s site), as long as you have working WiFi or Ethernet. Not the fastest way to recover, but better than staring at a dead machine…

Similarly, there’s a recovery partition on the Mac’s internal drive too. So if somehow the system becomes corrupt but the drive is still good, you can boot and reinstall just as beowulff described.