I have a 2017 27in retina iMac booting off of a (stable) DIY m.2 usb drive (controller: Realtek RTL9210 NVME). I upgraded to Monterey (public release - NOT beta) on Oct 25, the day it was released. It seems to have installed macOS 12.0.1. It upgraded and booted fine, and I interacted and configured the system (I changed app settings that were new with Monterey). When I shut it down (night) and booted it up (morning), the boot progress bar wouldn't cross 1/2 (everything else was normal). I tried booting in safe mode, but got no luck. I reinstalled Monterey with recovery mode (DID NOT WIPE DISK). However, I had the same issue. I tried safe mode again, no luck. I reset NVRAM and tried again, safe and non-safe (no luck). I booted into verbose mode to get the output, and it didn't seem like something I could fix. Here is the output:enter image description here

Finally, I tried booting on a 2015 iMac 5K. No luck there either.

I needed my Mac, so I reinstalled Big Sur (fresh) from an external boot drive and used a TM backup to restore my data. Unfortunately, this means I cannot perform any more tests.

My main questions are, what went wrong (curious), and if/when I can install Monterey again (I would highly prefer upgrading, even if I have to wait a month or 2). I would prefer not to, but am fine if I need to re-install Big Sur, but I would not like to right now, so I will most likely execute suggestions in a month if there is not a high level of certainty.

P.S: the only kernel extension I have that I know of is VirtualBox

Thanks again to all who answer my question.

Edit: see the solution I posted

2 Answers 2


Are you using external hard drive? Some people reported extremely long boot times (30+ minutes). Try to leave your mac booting for an hour, maybe it will boot up. If that's the case, as for temporary solution: let your mac sleep, instead of shutting down, till fix comes out. https://discussions.apple.com/thread/253302798

It seems there’s a problem with USB devices: https://discussions.apple.com/thread/253303875 https://discussions.apple.com/thread/253308334 Try to remove all external peripherals while booting up, including mouse and keyboard.

Another similar issue:

https://www.reddit.com/r/hackintosh/comments/qgcw3z/long_boot_after_monterey_update/ Maybe try to disable bluetooth

I have 2017 iMac 27 retina myself, it boots in 20 seconds, internal SSD.

  • Thanks for the input. I am using an external SSD. As I stated before, I had to downgrade my main machine to big sur, so I can't test. However, I have a 2015 iMac and clean external drive that I can install Monterey on to test. If this is the issue, ill wait a month before installing Monterey, as for my main machine, turning off Bluetooth (due to trackpad gen1 - no lightning) or waiting an hour for boot are not viable options. Oct 29, 2021 at 20:33
  • I tried to recreate the issue with a 2015 iMac and a sata ssd, but I can’t recreate the issue. From the threads you provided, it seems to be an issue with Realtek rtl9210 nvme, and I won’t try on my main machine, as I need that to remain stubborn. Real bummer that I have to stay on Big Sur for the next month, as I was counting on hopefully getting a Big Sur 11.6 issue with my monitor and the passwords tab. Oct 30, 2021 at 0:00

To help anyone with a similar issue, I got a jm583 enclosure from Amazon, swapped my Big Sur ssd into there, booted and upgraded to Monterey, and then the Mac booted in 2 minutes (versus 30). However, this still was not normal speed (45 sec), so I did a clean install and restored from a TM backup. After doing this, the boot time was reduced to 45 seconds in the JM583 enclosure. When I tested switching back to the (better) Realtek enclosure,the boot time increased back to 20 minutes, so I had to (and you will have to) permanently switch to your new enclosure.

*edit: my boot time went back to 2 mins after restoring. I guess ive just put so much on my mac that it boots slower now.

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