mid 2011 iMac tries to update itself to catalina?

[Berenod]

I recently bought a dirt cheap mid 2011 21.5" iMac for the wife in pretty much mint condition, when I got it, it had a 1TB go slow hard drive in it and Catalina on it (presumably using the DosDude patcher).

It, as can be imagened, due to de GPU not supporting metal en de go slow hard drive it ran horrendously slow, which is why the bloke I bought it from (he didn't do de Catalina upgrade, bought it himself like that) sold it for peanuts (50 € 😁 😁 ).

So, I opened it up, ripped out the HDD, stuck an SSD in and did an internet recovery which got me back to a supersmooth High Sierra running machine (with the help of Macfanscontrol to keep the fans from going into take off mode).

Few days later the machine says there are upgrades ready, installed them, and bam, got the stop sign on white screen indicating an OS got installed unsupported by the machine.

Re-did internet recovery, back to perfect running High Sierra, and now again it is indicating updates are ready.

Obvoiusly reluctant to install them now, but I fear I am missing out on High Sierra security updates (which still come through every so often).

Is there a way maybe the machine tries to always install a too high OS version because it once had Catalina on it? And where on earth does that get stored seeing as it has a complete new SSD in it? Maybe on the Apple update servers?

Or does de PRAM stores any such info to be used by the update engine? Seems a bit unlikely?

Anybody any guesses?

Cheers!

 

[Berenod]

----Update----

Just checked in the Appstore's update section, the update is NOT to a higher OS, it is indeed only the 2020-003-10.13.6 High Sierra security update.

Trying again now an see what happens. Maybe the previous update got corrupted?

Fingers crossed!

 

[fastlanephil]

I’m not certain exactly how that patcher works. Maybe it effects the firmware. If it does something like that maybe there is a way to reset it like you can with the firmware hack for the 2009 4,1 Mac Pro to a 5,1 Mac Pro. That info would be at his site.

macOS Catalina Patcher

You can check at select the updates you want by selecting “more info” .

Update macOS on Mac - Apple Support

Use Software Update to install updates and upgrades for macOS and its built-in apps, including Safari.

support.apple.com

 

[Fishrrman]

TURN OFF all options to do "automatic" updates.
When updates are available, think long and hard about whether you really want them, or not. You're under no obligation to accept them.
When you DO an upgrade, do not check a bunch of them and run them all at once.
Do them ONE AT A TIME. This way, if something goes wrong, you know which update is causing the problem.

 

[Jumme_Cph]

Google brought me here. Know Im a bit late but in case anyone else passes by and wondering.

I have previously encountered the exact same problem when iMacs intend to install firmware updates in connection with OS software updates. The error arises because the firmware requests to utilize an hidden area of the HDD while updating, that your SSD don't possess.

Alas, the only solution is to take out the SSD, put in AN ORIGINAL Apple HDD (any random one won't work), and then do the update. Then swap back.
IMO newer revision firmwares which often includes noticeably hardware updates, is worth the trouble.