What is the symbol of a circle with a slash through it, white on black screen?

Has anyone experienced their monitor (and it's not the monitor; I've checked) showing a black screen with a white circle with a slash through it? It is directly related to my Mac Mini. I'm wondering if the Mini's video function is dead, though it's only 3 or 4 years old.

It appears with two different monitors, and when I hook up those monitors to another computer, there is no problem. I had upgraded to High Sierras recently, but not THAT recently, I believe.

Welcome to the forum.

Nope, that symbol means there is no bootable device available. Either the drive has died (likely) or the files on the drive are corrupted and the system is unbootable because of that. You can try booting from an external drive and then use Disk Utility to first repair the internal drive, and if that fails, to reinstall it on the new drive you will have to put in it. You do have backups, right?

It could also mean that your Mac can't find its start up disc. Try booting while holding down the Alt key and see if you get a disc icon on the screen.

Or for a Mac keyboard hold down Option.

MacInWin said:

Welcome to the forum.

Nope, that symbol means there is no bootable device available. Either the drive has died (likely) or the files on the drive are corrupted and the system is unbootable because of that. You can try booting from an external drive and then use Disk Utility to first repair the internal drive, and if that fails, to reinstall it on the new drive you will have to put in it. You do have backups, right?

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Thank you! I was afraid of that. I will try booting up from our MacPro (that would be an external drive, right?).

So you're saying I can have a new drive installed in this 2014 Mini Mac? What is the advantage of doing that over buying a new Mini?

I am extremely ignorant about these matters, so you won't be surprised to hear that no, I haven't backed up. ??

harryb2448 said:

Or for a Mac keyboard hold down Option.

Click to expand...

I tried both Alt and Option; with the latter, the hard drive image came up with an arrow pointing to it. I clicked on the arrow and once again got the slashed circle... have also tried the safe mode business. Will now try to boot from another source. Appreciate your quick answers!

Thank you! I was afraid of that. I will try booting up from our MacPro (that would be an external drive, right?).

Click to expand...

No, I'm pretty sure that you can't do that. An external drive would be an external USB drive that would contain a backup clone(a bootable copy) of your Mini's hard drive.

Thanks. Very good of you to respond on a holiday!

I don't have a backup clone of my hard drive, alas. Think I'll have to take a trip to a Mac store tomorrow and fork out megabucks...

This exact same thing happened to 2016 MBP. Less than a year old. Thank goodness it was still under warranty. They had to replace the logic board and hard drive.

Thanks for the bad news! I've had Macs for decades; never had a serious problem before. Everything's going downhill! Way past the warranty on this one, I'm sure. Fortunately I never recycled my prior (2009) Mac Mini, so I'll try using that in the interim. It's just a relief to know this has happened to someone else...

So... I took my Mac Mini into the Genius Bar at the Apple Store today. They seemed very familiar with the symbol I was getting (white circle with slash through it against a black screen). Called it the "Prohibitory" symbol, and asked if I'd upgraded anything recently. Yes: I had upgraded the OS to High Sierra. Apparetly that OS uses a completely new file-formatting system than all older OS's, and causes things to go kablooey. My genius got my Mini working again in about 45 minutes, but was unable to save its data. At least I'm now back with Sierra, and will never upgrade again! The fix was all free, but had I not upgraded in the first place, I wouldn't have lost my data, so I can't feel all that thankful to Apple... Thanks again for your advice, and beware of High Sierra!

Alas, another "should have backed up" story. Sorry for your lost data. Take those mega bucks and invest in an external hard drive to use for back ups!!

Sounds like something went wrong in the installation/upgrade process. That could happen with any upgrade on any OS. That's why most of Apple's own documentation suggests doing a backup first. This update hade the additional possible complication of changing the underlying file system.

Yes, yes, I am fully humbled and always knew I should be backing up... though I never saw any warning to back up before upgrading. I am from the ancient era of printed Apple manuals and an absolute belief in "with Macs nothing can go wrong." As I have been retired for many years, nothing I've lost is priceless (well, we'll see, won't we?!?). It almost feels good to start cyberlife with a clean slate... and of course I do have my Mac Air, iPad, and smartphone to draw on. I apologize to all if I seemed to blame Apple for my own ignorance. And thank you all again.

As someone who has lost data before to both human error and lack of backups I feel your pain. I'm not sure if the OD download pages in the App Store mention backups but it is mentioned on their site if I remember correctly.