Catalina upgrade broke my iMac

This is a common problem with Catalina OS. Apple has taken a new approach by installing this OS on it's own partition. This isn't working reliably with updates.

1. Software update does aggressively push Catalina OS (see image below)
2. Backup your Mac using The best backup software included with your apple OS 'TIME MACHINE'. $70 US for a backup drive.

Once backed up disconnect your backup drive and leave disconnected when updating to a new Mac OS.

3.I highly recommend installing Mojave or High Sierra Mac OS onto your Backup Drive before upgrading to Catalina OS.

4.If you were tricked into upgrading to Catalina before you were ready. You will have to erase your 'Macintosh HD' to return

to the previous Mac OS.

5.Boot from your Backup Drive OS.

6.Goto Utilities/Disk Utility open, Select our Macintosh HD and choose Erase. Use AFPS format no encryption.

7.Install the previous OS that matches what you were using when you did a time machine backup.

8.Go through setup process and setup a generic user. When completed check for updates and apply.

9.Once updates are completed and you are signed into your generic user plug in your backup drive. Click decide later.

10.Goto Utilities/Migration Assistant Open, Proceed with the prompts and select your 'Time Machine backup'

11.It will search and show all the user folders and apps. select all and follow the prompts.

Hoping you have a better Mac OS experience remember BACKUPs save a lot of trouble.

Its not broken. I dont know why you keep thinking its broken. I gave you a link to show you how to downgrade back to Mojave. Did you check that out and give it a try? You need to follow the steps to go back to Mojave.

Here's the link again: https://www.imore.com/how-downgrade-macos

Heres something from Apple: https://support.apple.com/en-us/HT204904

Being 4 years old I doubt you have any warranty support. The Genius Bar probably also told you they could reimage it for you for a fee which, judging by your reaction in here, you probably said no.

Have you tried this to validate your hardware on your iMac?: https://support.apple.com/en-us/HT202731

If the extended test passes then you simply have a software issue and all you need to do is revert back to Mojave.

Sounds to me like your solution is to go back to Mojave to be honest. Catalina is a 64bit ONLY operating system. You were not forced to upgrade to Catalina. Actually you had to go into the App Store and specifically find Catalina to install. You could have stuck with Mojave and received updates only for Mojave. Why you are upset with Apple because you chose to go to a 64bit OS, without checking to see if all your apps and hardware were compatible, is beyond me.

I have upgraded a 2012 Mac Mini, 2013 MacBook Pro, and my 2019 iMac to Catalina. Each had their own upgrade glitches that I had to overcome (the mini and MBP were stuck on the "preparing desktop" screen and the 2019 iMac had a keychain issue). However none of my issues were related to trying to run 32bit apps on a 64bit only operating system. They were just small things I figured out and overcame. Things, I will admit, Apple should have prevented before releasing this OS but the issues were minor enough I didn't care to fix.

The simple solution here would be to go back to Mojave for you. Here, from a quick google, is a step by step guide on how to do that: https://www.imore.com/how-downgrade-macos

None of my previous software and devices works with Catalina. It is a disaster. Didn't someone anticipate this? I now have £1500 of useless computer

I did not see any warning about possible problems especially on the scale that happened. I have three DVD's that don't work (£225 ), Samsung 1810W printer taken over by hp who indicate on their site that they aaren't supporting OS10.15 at present an Epson printer V600 which has given me EPSON 2 software which seems to work in a limited fashion.

Catalina as usual produces a lot of new gewgaws i wont use and is a pain in the B.. Once I get this lot (hopefully) sorted out no more upgrades for me

You don't want help. You even marked your thread as "solved" by another ranting poster. If you really want help then I suggest you start a new thread and provide details of specific issues so that we can try to help you.

I am not ranting . I upgraded my MacPro in good faith and never expected the consequence to be that neither my printer nor my Scanner would stop working.

I am not used to the discussion group this is my first use so if was all over the place I apologise .Until you know what it is all about it is not obvious how to go about setting out the problem.

The problem is as stated in my latest above statement. At present hp don't support OS 10.15 so where do I go from here-apart from re-installing High Sierra?

The details are as stated in

If HP does not support Catalina you'll have to take that up with HP. They may have a 64 bit upgrade for their product. I wonder why you upgraded to a 64 bit only OS without first checking that your apps were all 64 bit.

It was not made clear to me who is not completely computer friendly what the consequences would be. I do not remember seeing anything on the upgrade script about consequences. The EPSON V600 works after a fashion with the EPSON 2 software but is not as good or as flexible as it was.

I repeat, the full consequences were not obvious to ordinary users like myself who were exhorted to upgrade by Apple on the the premise of checking for updates and updating as we usually all should in the normal manner.

We expect incremental improvments as has been common throughout upgrades, not a complete sea change that this is.

Apart from that how do I check all my apps are 64 bit and secondly I know very well that a lotof the material on my computer is quite old anyway and probably 32 bit but still useful. In my inocence I assumed the software would convert 32 bit to 64 in some fashion not make a lot of my previous content unworkable.