Restoring corrupted "AppleAPFSMedia" on 2017 iMac

You are booted into a very old OS there, so I would suggest booting into Internet Recovery Mode using Command + Option + R to attempt to access the online Ventura installer instead of the Sierra installer you are currently accessing.

If the iMac can still be booted normally, then I would highly recommend you first create a bootable macOS 13.x Ventura USB installer using the information in the following Apple article so you have more options available if Internet Recovery Mode gives you problems.

Create a bootable installer for macOS - Apple Support

When you go to erase the system, you will want to select the Fusion Drive item to erase if it still exists. Within Disk Utility you may need to click "View" and select "Show All Devices" before the Fusion Drive item & physical drives appears on the left pane of Disk Utility.

Just in case the Fusion Drive is split, you may need to rebuild it by using the instructions in the following Apple article:

How to fix a split Fusion Drive - Apple Support

FYI, here is an Apple article for everything you need to do when selling or giving away a Mac (the erase & reinstall step can vary a bit with some Macs):

What to do before you sell, give away, trade in, or recycle your Mac - Apple Support

You're in good hands with HWTech here!")

Instead of restore try this...

To start up from macOS Recovery, turn on your Mac and immediately press and hold ...

Command (⌘)-R

Installs the latest macOS that was installed on your Mac.

katie_mac wrote:

Hi - I just wanted to let you know that I haven't been able to get the Mac up and running. I attempted Command+Opton+R and the Ventura installer window did appear, but there was no clickable drive visible to download to.

That may be due to the broken nature of macOS on the internal Fusion Drive which could be due to file system corruption on the internal drive, or a hardware failure with one of the drives (most likely the hard drive portion of the Fusion Drive).

Since you were trying to "Restore" the system previously, it implied you were interested in a clean install of macOS by first erasing the drive. If you erase the Fusion Drive, then you should be presented with a location for installing macOS. If the erase fails, it would likely be due to one of the internal drives failing.

I then tried to create a bootable installer, but neither of the other Macs in this household will allow a download of Ventura (or Sierra) as one Mac is too new and the other too old.

A bootable USB installer would not change anything regarding the issue you mentioned regarding "no clickable drive visible to download to".

I've now had to give up as it's way beyond my skill level. I've booked the 2017 iMac into a nearby computer repair shop, and I'll just have to hope for the best.

I understand.

FYI, I would not spend any money on repairs to this iMac due to its age. If the tech finds one of the internal drives is failing, then the simplest solution to keep using this iMac working would be to have macOS installed onto an external USB3 SSD & boot the iMac from the external SSD. That would allow you to re-purpose the external SSD in the future to work as an external data drive or backup drive once you finally retire this iMac so the money invested in the external SSD would not be lost. A tech should be able to assist you with this option.

If you go for replacing the internal drive, then I would suggest replacing the Hard Drive with an SSD (Crucial MX500 series is good or an OWC Mercury Extreme 6G SSD are the best choices for compatibility....avoid the Crucial BX500 SSD at all costs). Not all SSDs are compatible with all computers and many internal SSDs tend to be low end junk these days.

You should also consider a new M-series Mac since they are the future of Apple right now. Even the lower end M-series models will probably be as good or better than this iMac. Just something to consider.

Please let us know how things go. And good luck.