Are there some apps that won't be supported by Catalina because they are not based on sufficient "bits"? What do I do about that?

The issue is related to apps that were designed to work on 32-bit systems. Most apps have been upgraded to 64-bit equivalents, but not all of them. macOS Catalina does not support these older 32-bit ones.

If you require using particular 32-bit apps going forward, you have a few choices:

• See if the app developer has provided a 64-bit version.
• Hold off from upgrading to macOS Catalina
• Upgrade to Catalina, but run a Virtual Machine manager, like Parallels or VMware, to run a VM of an earlier macOS version that still supports these 32-bit apps.

paulaingeneva wrote:

I'm about to upgrade from Mojave to Catalina on a 2016 MacBookPro, but I think there are some apps I have that were built on a "bit system" (I don't know the right term) that is not supported by Catalina. I think I have to do something to upgrade or change them in order to continue to have access once I upgrade to Catalina, but I don't know (a) how to identify such apps/programs, or (b) what to do about it. Advice is appreciated.

> (Option key) System Information>Software>Applications

Locate all 32-bit apps in System Info

http://osxdaily.com/2018/03/06/find-32-bit-apps-mac/

Keeping your software up to date is how you go about getting 64 bit versions compatible with Catalina.

Additionally, here’s how you can check for 32-bit apps on your system.

https://support.apple.com/en-us/HT208436

+1

This free utility will make things easier: https://www.stclairsoft.com/Go64/