Michael Graubart wrote:
Thanks v. much, D.I. Johnson. Actually I accidentally did try starting the upgrade and stopped it just in time, but admittedly I did not. get as far as actually downloading the installer. I'll try agaain.
If the installer launch after download you can quit it like any other app—however , this has proven to be ineffective aginst the daily update notices, unless that installer is actually run.
(The installer will sit harmless in your Applications folder "Install macOS Catalina.app")
A temporary fix between shutdowns/log outs is from the terminal.app copy and paste:
sudo softwareupdate --reset-ignored
(please note your psswd will not echo on screen—type it in anyway to proceed)
relaunch System Preferences>Software update
Then to suppress the red badge icon on the Dock, is one more Terminal command, copy and paste:
defaults write com.apple.systempreferences AttentionPrefBundleIDs 0 && killall Dock