Help Needed to Update Vintage OS X

[Sharkyboy43]

Hi all

Self confessed tech novice here, so any help or advise massively appreciated. I have an old 2013 iMac (A1418), and it was running Big Sur, which I believe is the latest it would update to.

Now it's vintage I've bought a newer model but would hate to see this old one go to waste and want to sell it, but when I wiped it, it came back on with Mavericks 10.9.5. It's not giving me the option in software updates to upgrade any more. Is there anything I can do?

Thanks in advance, and apologies if there is some important info needed that I've failed to mention, but just ask.

SB

 

[Bigwaff]

Boot into Internet Recovery (Option-Command-R) and you can install latest version of macOS supported by your hardware.

Use macOS Recovery on an Intel-based Mac

Learn how to use macOS Recovery on an Intel-based Mac.

support.apple.com

Best to use an Ethernet wired connection as Internet Recovery over Wi-Fi can be sketchy. Be very patient as Internet Recovery will take a very long time to boot as it has to download everything from internet.

 

[Sharkyboy43]

Boot into Internet Recovery (Option-Command-R) and you can install latest version of macOS supported by your hardware.

Use macOS Recovery on an Intel-based Mac

Learn how to use macOS Recovery on an Intel-based Mac.

support.apple.com

Best to use an Ethernet wired connection as Internet Recovery over Wi-Fi can be sketchy. Be very patient as Internet Recovery will take a very long time to boot as it has to download everything from internet.

Thanks for this @Bigwaff, apologies I should have explained better, this is exactly what I did do, via Utilities, and yet it received back to Mavericks even though it had been running Big Sur previously. that's why I'm confused by it all!

 

[Bigwaff]

this is exactly what I did do, via Utilities

I suspect you held down (Shift-Option-Command-R) and booted into Internet Recovery. This version of Internet Recovery installs the closet version of macOS available to version originally installed on iMac when shipped from factory. Mavericks sound about right.

 

[Sharkyboy43]

Darn it, is there any way back from that?

 

[Bigwaff]

Boot into Internet Recovery and install latest macOS compatible with your Mac (Option-Command-R).

 

[Sharkyboy43]

I've tried that, and it's only giving me the option for Mavericks, not Big Sur

 

[Bigwaff]

I've tried that, and it's only giving me the option for Mavericks, not Big Sur

If Big Sur was installed then it had to be using Open Core Legacy Patcher as Big Sur (macOS 11) is not supported by your iMac hardware. Latest compatible version of macOS is Catalina (10.15). If Option-Command-R version of Internet Recovery doesn't present Catalina, you'll need to download Catalina and create a USB installer on another Mac... unless you can get the App Store to work and upgrade your way to Catalina, one macOS release at a time.