10/24/2019 Update: I still recommend waiting to install macOS Catalina. In my experience, there are a number of bugs and anomalies in the initial release.
An excellent discussion and advice on waiting to upgrade to Catalina, as well as changes regarding Carbon Copy Cloner and clone backups:
10/7/2019: Apple just issued a surprise release of the next version of Mac OS, known as “Catalina”.
This release breaks older, “32-Bit” application software, meaning some programs will simply not run.
I *HIGHLY RECOMMEND* waiting to update to Catalina and only after doing an inventory of your mission-critical apps to make sure they are 64-bit ready.
***IF*** you do decide to upgrade, make absolutely sure you have a bootable clone backup of your computer BEFORE upgrading to Catalina. Do NOT update that backup for a few days or up to a week after you upgrade, or you won’t have the ability to restore back to your pre-upgrade state.
More information: https://tidbits.com/2019/10/07/macos-10-15-catalina-ships-upgrade-with-caution/