OS X Mojave Calendar won't open file
For a few years I had Calendar open a Backup script at a specific time in the morning. Now I can't even set up the event and save this function. The Event stays, but the only alarm it will save is a reminder.
The problem seems to have manifested fairly recently, but I haven't run any new upgrades for a while. (And no, I'm not upgrading the OS; I have legacy stuff here I need to use every day.)
Any help would be appreciated.
Mac mini, macOS 10.14