Mojave upgrade problems...

[FedoraTime]

Hi, I have a 2013 iMac. It's running on Mojave currently, I want to upgrade it to the OLDEST supported OS, which I believe is Big Sur.

In Software preferences I clicked to upgrade to Catalina (which seemed sensible given past bugs of skipping past Catalina). The process completed, so I am now running on Catalina, I expected to see "Upgrade to Big Sur" in Software prefs, but it's not there. It says my machine is up to date?!

I'd be grateful for any idea how to move from Catalina to Big Sur from here, apparently without any help from Apple's Software Update facility!
Thanks

 

[CoastalOR]

Maximum Apple supported macOS for a 2013 iMac is Catalina (10.15.7).

Big Sur is not supported by Apple

macOS Big Sur is compatible with these computers - Apple Support

You can install macOS Big Sur on any of these Mac models.

support.apple.com

 

[FedoraTime]

Dammit! What a waste of a great machine (32gb RAM, beautiful screen, 2TB SSD...)
Oh well, I refuse to waste, Linux here we come. Nice knowing you Apple! (Not really)
Thanks

 

[DeltaMac]

OCLP works quite nicely on that 2013 iMac. I have done that (a 2013 21.5-inch), using Ventura currently.
That would get you a long ways down the road, before you would need to go further.
And, that would allow you to continue on with the Apple family you know and love
(Still considering going to Sonoma. It's a work computer, so I don't like to jump ahead too often... )

 

[FedoraTime]

Sorry, I haven't a clue what you mean! What is OCLP? You're running Ventura on a 2013 machine? Pray tell more!
(You're talking to someone who had to look up what Sonoma is. )

 

[DeltaMac]

OCLP (OpenCore Legacy Patcher)
It is software that offers a method to run newer Mac OS versions on older, unsupported Macs
It can give you a newer operating system that gets close to what you would have with supported Macs.
It's not always perfect, such as an extra few steps that you have to take each time when updating your patched system.
But, it can work well enough for many users to continue another few years with otherwise-obsolete Macs.
It's the only way that I can run the latest Mac system version on an Early 2008 iMac (that Apple only supported up to El Capitan (OS X 10.11). It's an old Mac that I use as a hobby system, and for a fun project. Even with an SSD, it's kinda slow -- but, it runs the latest system. The 2013 iMac that I have runs MUCH better, but it has more RAM, and an internal upgrade to a PCIe SSD, so fast drive, more than sufficient memory, I should get another 5 years or so from that.

 

[rin67630]

In Software preferences I clicked to upgrade to Catalina (which seemed sensible given past bugs of skipping past Catalina).

I hope you have modified it to use a SSD. Catalina has converted the disk to APFS, which is a slow HDD killer.

 

[FedoraTime]

I hope you have modified it to use a SSD. Catalina has converted the disk to APFS, which is a slow HDD killer.

Not sure I understand. I have an SSD installed. Should I do something else? thanks

 

[FedoraTime]

OCLP (OpenCore Legacy Patcher)
It is software that offers a method to run newer Mac OS versions on older, unsupported Macs
It can give you a newer operating system that gets close to what you would have with supported Macs.
It's not always perfect, such as an extra few steps that you have to take each time when updating your patched system.
But, it can work well enough for many users to continue another few years with otherwise-obsolete Macs.
It's the only way that I can run the latest Mac system version on an Early 2008 iMac (that Apple only supported up to El Capitan (OS X 10.11). It's an old Mac that I use as a hobby system, and for a fun project. Even with an SSD, it's kinda slow -- but, it runs the latest system. The 2013 iMac that I have runs MUCH better, but it has more RAM, and an internal upgrade to a PCIe SSD, so fast drive, more than sufficient memory, I should get another 5 years or so from that.

I am frigging blown away by this! Doesnt seem beyond me to do it either (https://yewtu.be/watch?v=eGR2qGw9lG8)

We have several old macs in the family, a 2011 mac mini for TV machine which is buggy as hell due to no updates. I am definitely gonna try this, amazing, thanks!

 

[rin67630]

Not sure I understand. I have an SSD installed. Should I do something else? thanks

Then you are fine. macOS should run on a SSD from Catalina upwards.