Downgrading Catalina 10.15.6 to 10.15.3

Hey there! Did you upgrade from Mojave to Catalina? Or just from 10.15.3 to 10.15.6?

If you have a Time Machine backup, you can boot to recovery mode, and restore the backup from the date you had the version of OS you need.

This would erase everything currently on your hard drive, and replace it with what you had on the time of the backup, so if you have data saved since the update or upgrade, you can save it to an external drive or iCloud etc. first.

This process would take you back to the version you need for Pro Tools to work, probably the only way to do so, unless you have a bootable installer created with that OS version before hand.

So if you really need Pro Tools working again and their current updates aren’t compatible that should work, hope it works out! (Or that a Pro Tools update comes soon that does work)! Cheers!

This article may explain it better than me:

Restore your Mac from a backup:

https://support.apple.com/en-us/HT203981

No worries, hope it works out okay, Time Machine really is a life saver in many ways, I always keep auto backups, and even have a separate backup at times when possible, for reasons just like this. Cheers.

I have just had a look at the Protools website and Protools first is supported in 10.15.6,

and Protools and Protools Ultimate are also supported in 10.15.6, with some caveats,

see if these affect you.

https://avid.secure.force.com/pkb/articles/compatibility/Pro-Tools-System-Requirements

Never have your mac set to auto update.

Open System Preferences> Software Update and uncheck Automatically keep my mac up to date.

Have you tried it with 10.15.6? You cannot downgrade to 10.15.3. You can downgrade to Mojave but there is no way to upgrade Mojave to 10.15.3.