Calendar loses custom "open file" alerts On a Mac with High Sierra 10.13.6 Calendar loses any custom alerts linked to opening a file. I tested on macOS Mojave 10.14.6 and Calendar keeps those alerts and shows them:



On High Sierra, the same procedure shows no such alert and does not open the file, even after restarting Calendar. Here is the event:



Calendar also fails to display a custom alert of email, but runs it nonetheless.

In the meantime, I am running calendar alerts with Automator following this post. The reason is that I want to run an AppleScript as an alert, which after Mountain Lion I would need to do by saving it as an application bundle and opening the file.

Why does this happen and how to fix it?
This drove me crazy at one point too.  Make sure you are putting these events onto a local calendar, and not an iCloud calendar.  File open alerts won't work unless they are on a local &quot;On My Mac&quot; calendar.