Catalina, I wish I'd never installed it

I agree with you. Inept leadership is rampant these days.

The latest update to Mojave prevents:me from turning off Catalina upgrade nagging - Grr!

Sigh. Fixing it until it’s broken.

I know this is old, but have you tried disconnecting everything from your computer except for a keyboard and mouse (preferably not wired) and seeing if the problems go away? IME this is a good step for really weird things, especially crashes.

Obviously, a brand-new user account is also a useful troubleshooting issue, but in this case it sounds a lot like there is some hardware that is mucking things up. If you hav a machine with 3rd party RAM, take it out as well.

We have … six? Catalina Macs in the house and none of them are crashing. I provide support for several Catlina and Mojave Macs as well (a couple of dozen) and this is not representative of my experience. Remember, what you see on the Internet is the people who have problems, not the many many more who do not.

That said, there are a lot of little weirdzies (JJHO reference) with both Mojave and Catalina that are frustrating to deal with. The biggest one that bites me is then the Finder/GUI simply lies to me about the amount of disk space available. There seems to be some delay between deleting data and that deleting showing up in the Finder. At the best of times, the delay os several minutes. At the worst of times is it days or perhaps weeks. Why? No one knows.

Why has mail one again created a “On My Mac” folder and started dropping spam there? Who knows? When does it happen? No idea. Is it bloody annoying? Yes, yes it is.

I could go on.

But crashing? No. Drives vanishing? No. Apple apps not launching? No. All of those lead me to think the issues are lower down than the OS and are hardware related.

Really, it just doesn’t work. Mail servers will not talk to you.

Not brain-dead at all. ISPs publish lists of their dynamic pools of IPs specifically so that mail servers can reject connections from them. RBLS are the only thing keeping email viable right now (Well over 95% of attempted connections to deliver mail to my mail server are rejected, there’s that much spam). You’ll be hard pressed to find any mail server that will accept mail from a dynamic pool to their users.

(I’ve been doing this email server thing since last century, back before we had ever heard of spam email)

Well as you say, it’s an old post, I’ve long moved on, the Mac in question has no issues back under Mojave, runs smoothly. I tried your test, I tried all of them, it was with great reluctance that I lost days getting it back to Mojave.

We have six other Macs here, all on Catalina, all fine. All are laptops or a Mac Mini with the barest of additional elements. The Mac in question has a veritable slew of peripherals from extra monitors to multiple drives to scanners and printers and hubs of various flavours. Is there an issue with peripherals and Catalina? of that I can’t be 100% convinced but I’m inclined to think there is.

I just rolled an older Mini from High Sierra to Catalina. What a mess! Keyboards don’t work, performance is in the toilet. It appears it’s burning tons of cycles doing security scans over /Applications. I have no clue what the problem is with the keyboard. (Neither wired USB Apple keyboard or 3rd party Bluetooth keyboard are working.) Reboot times are appalling…

If this doesn’t get any better in the next day, I’ll roll that machine back to High Sierra, and be damned to Catalina! (This is one of the worst upgrade experiences I’ve had in 35 years using a Mac…)