Every time I restart my iPhone, my calendar seems to reset and all of my events disappear. Nothing else gets deleted, and I still have about 22 GB of free device storage. I'm wondering whether this is related to iCloud, but I don't want to pay $10 a month just to keep my calendar from being erased. How can I stop this from happening?
3 Answers
Check whether your phone is reporting that its storage is full, since that can sometimes interfere with syncing. If you still have around 22 GB available, though, storage space probably isn’t the cause.
Paid iCloud storage isn’t automatically required for basic calendar syncing. The important thing is which account the calendar is saved to and whether that account is enabled under Calendar settings. If the calendars disappear completely rather than merely becoming hidden, check the account settings and consider adding the events to a dedicated calendar account so they aren’t stored only locally.
The events may not actually be deleted. Open Calendar, tap “Calendars,” and check whether the account and calendar you normally use are still selected. Pull down on that screen to refresh the calendar data. You may be viewing a different or unselected account after the restart.
I checked, but the accounts aren’t showing up at all. The calendars themselves seem to be gone.

I previously paid for extra iCloud space, but even the smaller plan didn’t solve the problem. I’d need the more expensive plan for my other storage issues, so I’m trying to find a fix that doesn’t involve upgrading.