upgrading from Mojave to Catalina, why should I not upgrade?

Before updating, you should check for any 32 bit apps. If you have any, try to find updates or replacements for such apps as they will not work with Catalina. The upgrade went smoothly for me as it has for millions of other users.

mmillsap31 wrote:

What is there to consider for upgrading from Mojave to Catalina?

Typically you are always better off running the most current macOS your machine will allow—especially for the built in security features. It never payes to get too far behind in the hardware or software; just makes it more difficult to gracefully move your user/data/app etc fully intact.

Old app compatibility maybe one reason to hold back— you have to do your own homework here: https://roaringapps.com/apps

32-bit app compatibility with macOS... - Apple Support

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

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https://www.apple.com/macos/catalina/

macOS Catalina - Technical Specifications - Apple Support

https://support.apple.com/kb/SP803?locale=en_US

System requirements macOS 10.15 Catalina

macOS Catalina will run on all Macintosh computers that supported Mojave:

MacBook: Early 2015 or newer

MacBook Air: Mid 2012 or newer

MacBook Pro: Mid 2012 or newer

Mac Mini: Late 2012 or newer

iMac: Late 2012 or newer

iMac Pro

Mac Pro: Late 2013 or newer; Mid 2010 or Mid 2012 if upgraded with a recommended Metal-capable GPU

Always have a current backup plan in place before upgrading. Only in this way can you fall back if things go sideways for any reason.

3-2-1 Backup Strategy: three copies of your data, two different methods, and one offsite.

Boot clone https://discussions.apple.com/docs/DOC-10081

How to use Time Machine to back up or restore your Mac: https://support.apple.com/en-us/HT201250

Use DiskUtility Restore feature https://support.apple.com/guide/disk-utility/restore-a-disk-dskutl14062/mac

Been trying for weeks now to Upgrade my MacBook Pro from Mojave 10.13 to either Mojave 10.16 or Catalina.

The Mac Book I have is listed by Apple as compatible what is assumed is your File System is APFS

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Unless your File System is APFS (HFS+, Mac Extended - Journalized won't work) and agreeing with earlier posts 32 bit software will not work on Catalina. It continues to work on Mojave 10.13 on my machine.

Tried a trial on my Mac Book- made small partition and formatted it as APFS- Catalina loaded on that partition just fine