Calendar entries missing after iOS 26 update

A follow up to my previous message:

I restored my phone from my pre-iOS 26 backup. Apart from a couple of minor hiccups that went smoothly and all my calendar data has returned (yay!).

Never restored a phone from a backup before so it surprised me that:

1. The restored phone had iOS 26, not the iOS it had when I backed up.
2. I had to re-download quite a few apps, even Apple ones, but not lost any of their data.

A final comment. Like some others have commented, I also had a storage space problem when I first downloaded iOS 26. After I downloaded the iOS, WhatsApp told me there was insufficient space on the phone, so I removed a big pile of photos (I archive them on an external drive).

I tried yet another restart after opening up my calendar on my iPad and MacBook, and my calendar events came back. Perhaps you can try the same? My Shortcuts are still missing, though. Perhaps this is related to the "oversize" of the system data?

Please contact Apple and let them know as I’ve just called them and complained and they are saying it’s a “me problem” even though the last software update has lost my 15 years worth of inputted calendars

I restarted my phone and still all shared family calendar entries are gone. Luckily still on my Ipad! I guess I will have to manually go in and re-enter all these. I can’t figure out a way to add this calendar unless anyone else has a suggestion to retrieve the information.

my husband deleted me from the invitation and then resend an invitation through iCloud. I accepted it what it says is that I can only use this on a tablet or on a computer it does not give me the option of using it on my iPhone anymore so it sounds to me like this is a Apple problem

Same here. Also, missing some entire sections in my Shortcuts. This morning, the phone indicated that I was out of space, and the OS system data had taken up over 128 GB. A restart cleared that, but things are missing now—even apps!

[Edited by Moderator]

iPhone 11

Yes, same thing happened to me. Updated yesterday (01/10/2025) to iOS 26, and calendar now completely blank of data. I haven't tried recovering yet; I was hoping to get an answer here.

I backed up before the update, to my Mac Mini, but I don't know if I can just restore the Calendar or do I have to restore the whole phone then start again. I don't use iCloud to back up.

I'm experiencing a similar issue. All entries from a particular shared calendar are not showing up on iOS 26.0.1. I can see the entries on MacOS 15.6.1

I lost all my calendar entries from inbox, and I didnt up date.