High Sierra install issues and now can't find startup disk

Took MacBook to Genius Bar today. Guy went through initial process as I had done (in recovery mode) but no use. So, he tried to install Sierra and also no go. Then doing his "deeper" diagnostic check, says my SSD drive failed the check - this is the SSD drive that was working perfectly before I tried the High Sierra install!!! Quoted £714 to replace it!!!!!! How can a supposedly straightforward OS install do this to my MacBook?!??? Will phone Apple support tomorrow to complain

So I was able to "fix" mine:

1. I booted it in recovery mode. I attempted to re-install Sierra, but to no avail ("Permissions Denied").

2. Then I tried to apply first aid to the disk; the first aid failed a couple times in a row.

3. I gave up and then returned to it in the morning.

4. For some reason that I do not understand, first aid worked in the morning.

5. Then I was able to restore the computer using a Time Machine back up.

It certainly wasn't ideal because I lost a few weeks of work, but MOST of my stuff is saved on dropbox so it wasn't the hardest thing in the world. What still stumps me is why first aid worked in the morning, but it was at least a happy accident.

Installed my new hard drive bracket and mine works now, so I guess after having my laptop for 5 years with no problems, the bracket did fail a day after my high sierra install (coincidentally). What are the chances....happy it's up an running though.

Do you mean First Aid reported everything was OK? If Apple Hardware Test stuck on memory there may be a problem there. If you've added RAM try removing it and test with the original modules.

I got same issue, i got mac pro 2010, after installing osx high sierra, I changed OS system to another disk (El Capitan) because some drivers was not working on new High Sierra (Fireface 400 audio driver).

When I tried to went back to High Sierra, boot disk disappeared.

PROBLEM SOLVED AT HALF:

On my Mac Pro I got 4 hard disk, I removed the hard disk with (El Capitan) old os system, and replaced it with the hard disk with High Sierra, so it started again working.

But...solved at half, because if I put in again the old hard disk with El Capitan, same issue is coming back.

I wish I would have seen this post before I updated to High Sierra. When I updated, I received the error message below.

I called Apple Care and the tech said that the download did not fully install. I pressed Command R and didn’t see the hard drive. I clicked on the Apple in the upper left corner and then clicked on boot disk, clicked that and the MBP rebooted. I ran the disk utility and found no errors. The tech said that I could just download the update again and it should be fine. Sorry I’m not a tech person, just a Windows escapee. It took approximately 45 minutes with no problems. Also, I downloaded both the recent supplemental updates with no problem in a little over 20 minutes for each. I’ve considered trading in my mid 2012 Mac but have since changed my mind. It still runs fine for my needs. It has 8 GB of Ram and a 500 GB hard drive.

A nice man at Apple support talked me through this and it worked. Apparently the problem is caused by High Sierra reformatting the drive to a new system.

Same here. 2012 MacBook Pro, worked until High Sierra upgrade and now I get the blinking question mark. Tried everything I can think of...Can’t choose startup disk, nothing there. Time machine a no go. Can’t reinstall OSX or use disk utility because my computer isn’t seeing hard drive now. Removed hard drive and tried on another machine and it works properly and mounted. Have Genius appt next week, will update.

Upgrade to High Sierra went fine on my MacBook Pro 15.4" Late 2011. The next day it was running slow then froze so I rebooted. Ever since then all I get is the flashing folder with a question mark. I've tried internet recovery, set PRAM, rebooted holding various key combinations, etc. to no avail. After the hoops to finally get access to disk utility (takes multiple attempts and each attempt takes quite awhile) there's nothing there - my hard drive isn't listed. I did manage to access the Apple Hardware Test and it said everything was OK. Yeah, right.

I can't download High Sierra using my other MBP because it's too old to be compatible (mid/late 2007) so download isn't even an option per Apple.

The icing on this craptastic cake is I didn't verify my Time Machine backup - it must've failed because the last backup showing is MONTHS old.

I've removed the hard drive, put in an external case and plugged it into my old MBP and it doesn't even appear in Finder. Does that mean the drive has been corrupted and the information is lost?!

Same issue here. Bone stock 2013 MBP with Sierra already on it. Just innocently said yes to update. All looked like it was going well, but failed at end. Said to reboot, and rebooted to Question Mark Folder.

Let the fun begin!

I got same issue, i got mac pro 2010, after installing osx high sierra, when i decide to change startup disk, i can change it to previous version, but when i'm going to return to my high sierra version disk, os X Base system is not reconized .

I have done all of the above suggestions rebooting into recovery mode multiple times without success we see the Macintosh HD in Disk Utility run First Aid and it always says ‘appears to be ok’.

We are finally going to attempt to ersse and reinstall.

I’ve tried everything identified on this site, butvto no avail. In fact, I was able to get beyond the question mark, but only to reach a prohibitory symbol. I’m about to give up because it’s not worth paying Apple an absurd amount to fix a 2012 MacBook that was fine before this download.

This is my exact problem. Please tell me exactly how you reinstall the OS so I don't lose data. Where do I find the reinstall option. I am at the end of my tether, all because I followed Apples's instruction to update. I hate Apple 😟