My current install of Catalina has gone a bit wonky. Every other time I start it up it displays the circle with a line through it, so I do a hard restart and it will then boot into Catalina.

I'm trying to move to Big Sur and wondering if I should do a fresh install/reformat, or if i should do a Reinstall MacOS from the recovery screen.

From what I understand Reinstall MacOS just rewrites the OS files, but keeps everything else intact like document, downloads, apps, etc...?

Should I upgrade to Big Sur first? Or Reinstall Catalina, and then upgrade to Big Sur? Or just a fresh install? (Running an iMac Pro)

  • 1
    In all cases, you should promptly make a backup of all your critical data. Then an erase-install becomes reasonable and is the most effective way to reset “wonky” behavior. But that is a big hammer. If you are open to trying to diagnose and fix your issues instead, I would suggest starting by booting with verbose mode (CMD + V during boot) and showing us screenshots of your failed boot.
    – pion
    Feb 26 at 0:26
  • 1
    A key factor in determining the way to go is whether or not you have a current backup and, if so, what type of backup it is (e.g. Time Machine, etc)? In addition to this, can you clarify if your main goal is to upgrade to macOS Big Sur, or whether it is to sort out the "wonky" Catalina installation?
    – Monomeeth
    Feb 26 at 1:01
  • I am evaluating different versions of MacOS and from my point of vue: security and quality, Big Sur isn't yet to a level sufficient to work with.
    – dan
    Feb 26 at 15:12
  • Indeed I have several backups. I'm not quite sure what happened. I've never seen that screen before in the many years I've had Mac's. I think a clean install would probably be best. The transferring of files is always the biggest pain. I can restore from a backup, but I'd rather start fresh to make sure nothing would carry over from the current install.
    – v15
    Feb 26 at 17:05
  • What do you mean by "a bit wonky"?
    – dan
    Feb 26 at 18:05

The "circle with a line through it" is known as the prohibitory symbol. Typically this means that your startup disk contains a version or build of macOS that your Mac can't use. In your case it seems something else is going wrong, but, if I read between the lines correctly, it seems your main goal is to upgrade to macOS Big Sur anyway.

The best course of action is really to make a full current backup of your system and then reformat your drive before re-installing macOS.

You have a number of options open to you, such as using the Option-Command-R keyboard shortcut at startup to upgrade to the latest macOS that is officially compatible with your Mac (and assuming macOS Big Sur is compatible, then this will be what is installed).*

If using this option you'll have the ability to reformat your drive using Disk Utility first before opting for the Reinstall MacOS option. More information on using macOS Recovery to reinstall the Mac operating system is available on Apple's website: How to reinstall macOS.

Another option is to just create a bootable installer for macOS and then boot up from that to install macOS Big Sur. You can opt to fully reformat your drive before doing the installation. More information is available from Apple's website: How to create a bootable installer for macOS.

Regardless of how you go, the main thing here is that you're broadly following this order:

  1. make a full and current backup of your system
  2. reformat your drive
  3. reinstall macOS
  4. transfer across your files etc

Following this order means whatever is causing your 'wonky' Catalina installation really shouldn't come across with you.

NOTE: - Keep in mind that many users have had issues with macOS Big Sur, so whether you should make the jump yet is really only a decision you can make.

* If your Mac has the Apple T2 Security Chip and you've never installed a macOS update, this will install the latest version of macOS previously installed on your Mac.

  • Thanks so much!! I'm not quite sure what happened. I run a wide variety of programs and I'm sure at some point trying to mess with configurations with a driver of somekind it must have messed up the boot loader files. I have several backups and the OS runs fine when it does boot. Re: Big Sur - I keep up with many of the message boards, but what are the main reasons to not upgrade?
    – v15
    Feb 26 at 17:03

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