I just upgraded my laptop to Catalina as a test for the main computer.
I did this as shortly Apple will release Big Sur and i don't want to be more than 1 version behind.
I used Retroactive 1.8 to make Aperture compatible with Catalina.
So far so good.
The following work - Import, Rate, Crop, Lift and Stamp, Export,
Identified Problems:
- the stuck Activity Window with too many edits, (same as Mojave), requiring a Forced Quit.
- Edit with External Editor (Photoshop) has no progress in creating the TIF.
Minor issues were that all of my customised settings were gone.
I had to change Location of Imported images to Leave In Current Location.
I had to use Add Adjustments as required and then add each adjustment to the Default Set (Right side down arrow).
I can get by with this so Aperture will live on by the look of it.
Now I need to try and fix the other programmes that don't work, mainly accounts and monitor profiling.