Before you upgrade to OS X Catalina you may need to stop and assess the applications that will stop working. Catalina is what is called 64 bit. They are not at all compatible. Previous OSX version (e.g. Mojave) would have given you a warning about 32 bit applications that you are running. So I knew that Adobe Illustrator and Photoshop and some other apps would stop working when I upgraded to Catalina. But I was not prepared for how many applications would stop working!
Here are just some of the apps that stopped working wth my upgrade to Catalina:
I used it a lot to edit my Apple Address book contacts. It’s the only program thatI know of that can interface directly with Apple address book and export your contacts into a CSV file. A shame that there is no alternative.
Quicktime player 7
I had the pro version which allowed me to do some nice video editing and compression. The newer versions of quicktime do not have a pro version.
Requires $150 to upgrade to the newer version.
Adobe Photoshop and Illustrator
These products now only come as a subscription so I purchased Affinity Designer to replace them.
Sibelius First and Dragon for Mac.
These still worked on OS X Catalina until I purchased a new laptop. The Serial number validators don’t run in Catalina. That means Dragon and Sibelius will continue to run as long as you keep the same computer. I just upgraded my laptop and both Sebelius and Dragon asked me to re-verify my serial number. There is no way to enter a valid serial number under Catalina. So Catalina killed those two apps even though the apps them selves are 64 bit.
Fujitsu Scansnap Scanner drivers.
I have a Fujitsu Scansnap S1500 scanner that I used to import all my documents into Devon think pro. The Fujitsu scanner drivers that work in Catalina do not work with older Fujitsu scanners so now my $800 scanner is rendered useless even though it was working perfectly.
The bottom line is when you install Catalina a lot of your existing apps may stop working and you may need to buy new ones or upgrade them. For some applications that just means forking out some money but there are other discontinued applications that there is no alternative for Catalina. (e.g. iDVD, Bento, Quicktime Player 7 Pro, CSSEdit.)
I’d suggest waiting till you have a fair bit of free time before upgrading to Catalina, and after you upgrade give all your Apps a test to make sure they still work.