Mac mini late 2012 lost internal HD on upgrade to Catalina

[skallal]

I have an old Mac mini late 2012 that has been running Yosemite for at least 4 years now. Haven't used it much, but decided to upgrade it to Catalina as that's the latest version Apple allows.

So I was able to get it from the App Store. However the upgrade never successfully completed. It starts up with the Apple logo and shows the progress all the way to the right. But it's stuck there.

I've been able to boot up on a TimeMachine backup and can run Disk Utility. It's unable to mount my internal hard drive although it correctly reports the disk space. Also the Base OS X partition is still there and verified.

I'm using a Windows keyboard and Logitech mouse. The mouse is okay, but I have doubts about the keyboard. I can get a boot menu by holding down on Alt-R, but none of the other keyboard combos for recovery or safe mode work.

So how do I get the internal HD to mount? I'm more than willing to reformat it.

Help!!!

Steve

 

[mdgm]

Going straight from Yosemite to Catalina probably wasn't advisable.

APFS support was introduced in late Sierra versions and properly starting with High Sierra.

There are important Bootrom updates to properly support APFS. If those weren't installed yet then there could be issues.

Once the bootrom has been updated if you were to go to Yosemite again and update direct to Catalina that should work fine as the bootrom is not downgraded back to what it was before when you put Yosemite back on.

I think Catalina uses APFS by default even for hdd.

Do you have another Mac?

I would suggest downloading Yosemite or El Capitan or Sierra (https://support.apple.com/en-au/HT211683), creating a bootable installer, erasing the internal hdd using Disk Utility and installing OS X restoring from your Time Machine backup and updating to one newer version of OS X at a time. Install latest security updates then move to next OS X.

Going to Sierra 10.12.4 (or later) internet recovery is improved to have the option to go to the earliest still available OS X for your Mac or the latest OS X for your Mac depending on which key combination you press. If those key combinations aren't working it means that you are missing the important update. See https://support.apple.com/en-au/HT204904

 

[Fishrrman]

Can you boot to INTERNET recovery?
Command-OPTION-R

This is different from "the recovery partition".

If you can get to internet recovery, do so.
Then open disk utility.
Is there a "view" menu?
If there IS, does it give you the option to "show all devices"?

If so, choose that.
Now, look at the list on the left.
The top line should be the physical internal drive.
Click on it to select it, then ERASE IT.

I would try "Mac OS extended with journaling enabled, GUID partition format" first.

Does it erase?
If so, open the OS installer and start over.