Trouble installing macOS Monterey off USB--2015 iMac 21.5

[macbookm1airlover]

Good day, all.

I have a weird one for you, and I have tried to troubleshoot the best I can...but I am at a dead end. I inherited a (free!) 2015 iMac 21.5 (non-4K) with a dying/dead HDD. I ran First Aid on the disk, and it failed.

No problem...obviously knew about the dead HDD, so I rebooted into Opt-CMD-R on startup to get Internet Recovery Mode. I inserted a new 256GB USB 3.1 Samsung flash drive as I want to install macOS on that as opposed to the internal HDD. Formatted USB as APFS, and went to reinstall macOS Monterey from the Recovery Screen. It sees the USB, and it downloads Monterey in the Recovery menu. It even reboots into the black screen with Apple logo and a loading bar (25 mins remaining, etc)...until it comes to the final loading screen with the black screen / progress bar. It kernel panics and it goes into a loop. After the initial Kernel panic, it's just the loading bar with no Apple logo until it panics over and over again.

I decided to try Shift-CMD-Opt-R to load El Capitan on it...and it installs and runs beautifully off the USB. I was even able to load up to Catalina on it...but when I went to update Catalina (security update I believe) it just has the Apple logo with no progress bar...left it on for a day with no change.

I installed Monterey on the dying HDD, and after a couple of hours (days?)...it came with the setup screen.

Things I have done:

• Reset SMC/NVRAM
• Tried formatting USB as Extended Journaled
• Different USB ports
• Mac OS X El Capitan through Catalina works.
• SIP is enabled
• Apple Diagnostics (came back with clean bill of health)

I apologize if I am missing something blatantly obvious...but is there anything that would cause El Capitan to run just fine, but not Big Sur or newer? Does SIP need to be disabled?

I appreciate your assistance with this issue.

 

[Fishrrman]

"I inserted a new 256GB USB 3.1 Samsung flash drive as I want to install macOS on that as opposed to the internal HDD.
***
Mac OS X El Capitan through Catalina works."

There's your problem. (although it may not be obvious)

Simply stated -- you CANNOT install the most modern versions of the Mac OS onto USB flash drives, SD cards, or even some slow platter-based hard drives. It just won't install. This seems to be "by design".

You MUST use an external SSD, and it MUST be a "real" SSD, NOT a "flash drive" (with a limited controller). Some platter-based drives may also work, but you don't want them as a boot drive.

If you want to create a boot drive with Monterey, here's what I'd suggest:
- Get a modest-sized 2.5" SATA SSD (these are quite cheap, even 256gb would be fine)
- Get a USB3 2.5" external enclosure, like this:

SABRENT 2.5 Inch SATA to USB 3.0 Tool Free Clear External Hard Drive Enclosure [Optimized for SSD, Supports UASP SATA III] (EC-OCUB)

SABRENT 2.5 Inch SATA to USB 3.0 Tool Free Clear External Hard Drive Enclosure [Optimized for SSD, Supports UASP SATA III] (EC-OCUB)

www.amazon.com

The drive just snaps into the enclosure.

Now, boot to internet recovery:
Command-OPTION-R

... and try it all over again.'

IMPORTANT:
Once the internet utilities load, open disk utility.
Go to the "view" menu and choose "show all devices".
Now look at the list on the left, choose the new SSD, and erase it to "APFS, GUID partition format".

Then quit disk utility, open the OS installer, and proceed.

Good luck.

 

[macbookm1airlover]

Greatly appreciated! I did not realize I needed a proper SSD vs. 3.1 USB. I'll get those things you mentioned, and we'll see how it goes. Thank you!