High Sierra install is frozen

Success: I resolved this exact problem. When trying to install High Sierra, my Mac was stuck the black startup screen, stalling at either 90% or 100% completion between restarts.

I managed to get High Sierra installed without losing any of my files. Here is how I did it.

Failures:

• Resetting a billion times.
• Resetting PRAM.
• Resetting CMD.
• Using Safe Mode.
• Using Recovery Mode (It would freeze upon attempting to re-install the OS, and Disk Utility couldn't detect my drive).
• Using Internet Recovery Mode (Same as above).
• Looking at Verbose startup mode -- it said "Error 13" on the drive IO.
• Talking to the "geniuses" at an Apple Bar, as well as online tech support. They suggested either formatting my drive, or even buying a new drive. They had no inclination to dig into the problem and actually figure it out and fix it.

What worked:

• I put my Mac in Target Disk mode (hold down T upon startup).
• I connected my Macbook to another Macbook using a Thunderbolt cable. The other Macbook must be running High Sierra. If you don't have a friend with a Macbook, you might be sh*t out of luck.
• I made a backup of my files, in case things went poorly. My Macbook appeared as a drive on my friend's High Sierra computer, but dragging files over in Finder resulted in an error. I had to use Terminal and "cp" my files over.
• I opened Disk Utility on my friend's computer, and here are the steps I took:
  • View -> Show All Devices
  • My Macbook showed up, along with various "Container disks".
  • I ran First Aid/Repair on all of the various things I saw. Some of them threw errors and refused to repair, but that seems to have been okay.
• I then created a bootable USB installer as per How to create a bootable installer for macOS - Apple Support using my friend's computer.
• I ejected my Mac, disconnected it from the other computer, and booted my Mac onto the USB booter. I ran the installer from the USB stick, and it succeeded! After it completed, High Sierra booted up, and all of my files were present, unharmed.

This was a huge headache for me, and I hope that this writeup helps save your files. Don't necessarily listen to the Apple "geniuses" who say that a format is necessary.

I am seeing the same thing with my Macbook Air. It has been sitting in the middle of the install bar showing "calculating time remaining" for the last 14 hours.

I'd recommend no one upgrade yet until it is stable. It also fails on my Mac Pro.

in addition to that I have found in some occasions disconnecting anything thats not needed can help move the process along when it gets stuck. It's best to do this before you begin the install.

Its not uncommon for any and all OS X upgrades to get stuck in the last few minutes of the install and rebooting sometimes clears it up. this (bad) behavior is not exclusive to High Sierra but it's more the exception than the rule - at least I hope it is because I plan to clean install it on my 2010 Mac Pro when I leave for lunch and see what happens when I get back.

the connected device thing is rarely the sole cause and many times it's not even a cause but sometimes it very easy to unplug and rule it out. I'd try the reboot. Not too many posts about the installer taking out systems but maybe more reports later. I'm about to let 'er rip in about 35 minutes or less.

I had the same thing with MacBook Pro getting quite warm and stuck on progress bar with no other info like time remaining. I finally held down the power key until it turned off and then powered back on. It resumed the install and finished fine. YMMV and obviously bad things could happen but after this much time, you're likely going to have to do this anyway. Good luck.

That boots from the recovery partition, where you can troubleshoot, it will install Sierra I presume, as High Sierra isn't even installed on your computer. The procedure Benny B explains (hard reboot) works well if your installer is stuck, I had to do that as well.

Thought I would share what worked for me on my Macbook Pro 2016 with TouchBar.

Had the same issue. Tried upgrading directly from the installer, from recovery mode, from internet recovery mode, doing first aid in between, still no success.

Couldn't login anymore, so after recovering from Time Machine (5 hours... ugh) I created a bootable usb version of the installer. This was about 45 minutes ago and I'm already here writing this in High Sierra. Give this a go!

Good advice!

I had trouble upgrading from the latest bèta release since the App Store error'ed out every single time I tried to install the public release, probable due to the installed beta access utility, but luckily I had another Mac that was still on Sierra and was able to download High Sierra, put that on a USB Flash drive and install went smoothly from there on.

My problem on my 2012 MacBook Pro is even worse. Since updating from 10.12.6 the system is using almost 100% of the processor time, meaning that my user applications are at snails pace. Kernel_task is using 533% of CPU (not sure how this is mathematically possible - but hey ho this is an Apple machine, and they are never wrong).

People say ‘oh that is a faulty temperature sensor and you need a new motherboard’ (for £500? - yeah right).

However, I have a bootable copy of 10.12.6 on my external HDD and if I start up from that everything works fine. System processor usage between 5 and 10% until I start software.

So, why is my motherboard/sensor faulty on 10.13.0 but not on 10.12.6?

I could live with booting from the external drive permanently if it wasn’t for the bind of having to transfer bookmarks, iTunes libraries, etc., but why should I have to?

Well, Duh!!

Do you really think we would go to the trouble of asking a question here, if we had not tried all the blatantly obvious solutions?

My theory is that when anything goes wrong with an update Apple have pre-programmed a throttling process into the startup in order to get the user to take the computer to an Apple Store to pay vast amounts of money for a "repair" which is basically not necessary.

I say this because I have SSD Fan Control installed on the 10.12.6 boot copy, and when I start from this, the fans go to 6300 rpm almost immediately after the horizontal startup progress bar appears on the screen. All they have done is set a sensor to register 128C and Bingo!! pretend the motherboard needs replacing; but 2/3rds of the way across, the progress bar SSD Fan Control kicks in and the fans reduce to 2000rpm which is the value I have set them to.

Unfortunately, when you install 10.13.0 it automatically renders much Apple software to be incompatible with 10.12.6.

I'm afraid this is corporate arrogance beyond belief. Imagine buying a car, and if you drove above the speed limit for a few minutes or disconnected the car battery, the engine was throttled back to a maximum of 25mph until you took it to a garage for an expensive repair.

Dude. Not everything is about you.

I was answering the question of the person above to make sure when they say nothing happened that they had really powered down.

You seem to have problems that extend beyond your boot process....

Not everything is about me, says the person who is so self obsessed that he takes just 5 minutes to respond to a critical reply.

Do you not understand irony?

I will take "you seem to have problems that extend beyond your boot process" as an admittance that you do not have a clue what my problem is - but you feel you just have to reply anyway.