Missing events / randomly deleted events? (Yahoo)

If your events are completely gone or get randomly deleted, there's a 99% chance you are syncing with Yahoo! Calendar.

Lots of users unfortunately sync with Yahoo without knowing they do. Please see on how to find out if you sync with Yahoo:


How to find out if I sync with Yahoo?

  1. Open the calendar picker (2nd button on the bottom bar)
  2. Scroll down the list of Calendars until you see Yahoo mentioned

What's happening?

Yahoo! Calendar syncing is very unreliable and can cause random deletion of events on mobile devices.
We advise against using Yahoo! calendar for syncing and use iCloud or Google Calendar instead.

How to resolve?

If you are missing events, please be aware that this is not a Week Calendar issue, but a Yahoo issue: Yahoo is randomly deleting your events, due to problems on their side.

Please contact Yahoo! directly regarding this issue.

We advise against using Yahoo for calendar syncing, and use iCloud or Google instead.


Possible Solution

Yahoo! gave the following possible solution: https://discussions.apple.com/thread/3186946?start=90&tstart=0.
In short, Yahoo! advices to not sync via CalDAV, but use the built-in Yahoo! option when setting up a Yahoo! account on the iPhone via System Settings.