Jono Slack reminded me this week that Apple’s much-loved Aperture will no longer work under the new MacOS which is expected to be released on Friday.
This is because macOS Catalina will run only 64-bit applications and, since Apple ceased development of Aperture back in April 2015, it will become a deceased app when you upgrade.
If you do still use Aperture as your photographic library it is time to move to an alternative. At any rate, do not update to Catalina until you have made arrangements for your data.
This article on moving to Apple Photos or Lightroom will help. You can find other solutions, including some one-off applications, if you intend to use an alternative processing package.
It’s also a good time to check if you are still relying on old 32-bit applications that have not yet been updated — or, as with Aperture, have lost support and will never be updated. You can do this easily.
This Macworld article takes you through the process step by step so that you can sort your applications into 32-bit and 64-bit standards.