calendar is slow to respond after update to ios 15.1 on iphone XSmax

I have this problem as well on both iPhone 12 & iPad after upgrading to 15.1.1 - that said, I discovered today that it only happens when I'm on WiFi. If I'm on cellular, there's no problem. Not sure why the difference. Doesn't matter what WiFi network I'm on (home/work/public). But I've started to turn off my WiFi on my iPhone when I need to access/view the calendar. Not ideal, but a workaround until Apple can fix this with the next software update.

I upgraded to 13 Pro Max, same issue from scratch. My colleague had no issues and then it started acting up like mine. He has a 12. There doesn’t seem to be a common denominator in all of this except for Exchange. All the advice received from Apple did not work. I guess that Apple needs millions of pi$$5d off users to solve the issue. It is very disappointing.

So incredibly happy to have found these reports. Not really, because I’m dealing with the same thing, and it’s crushing me as I live by my calendar on my phone. I went to a store and they told me “it probably isn’t an update issue” but I looks like it is. Anyone find any answers on this?

I updated to 15.1 last night and also made various adjustments to privacy and location services based on an article I’d read. Found this thread today when my calendar was locking up and not adding events. Based on suggestions above I removed and reinstalled calendar. After reinstall I was asked and allow edge allowed calendar to track while in use. So far it seems to be working better after those two changes. I wonder if my problem had to do with adjustments I had made to location services.

I deleted the calendar app (not the calendar accounts) and then re-installed it from the App Store.

So far after one full day it seems to be working again with my two different work exchange accounts and a personal Google calendar. Fingers crossed it is a stable solution.

Thank you to everyone that has posted, especially about possible causes. Caching as a potential cause intrigued me. So as five minute experiment I tried the above.

Only minor annoyance was having to change the default calendar colors to what I used before by clicking on the “i” next to the calendar in “Calendars” at the bottom of the calendar app.

Has anyone had issues with contacts because of this update? I sort of lost like half of mine. They are still there when I manually type in contact info but not when I try to text them by name or email them by name.

I have an iPhone 8 and the system was recently updated to 15.1. Now my calendar has stopped functioning almost completely. It doesn't scroll beyond today's date and in some views the appointments are scrambled and can't be read. This effectively bars me from using my calendar on my phone, for either checking diary entries or making new entries, so I have to carry a laptop with me everywhere or carry a paper copy of my calendar with me wherever I go. This is crazy! Can Apple please sort this out?

Well, nope, negativ, the originally problem with iOS 15.1 couldn't be solved by changing this setting to 2 weeks. This is my setting since I use an iPhone back in 2008/9 ... that issue got solved with iOS 15.2. Everything else is a different issue ...

The issue is also reported and discussed here:

https://origin-discussions-us.apple.com/thread/253295714

Another thread is reporting the same issue:

https://discussions.apple.com/thread/253311143

Widely discussed here (no fix yet)

https://discussions.apple.com/thread/253295714

It’s becoming worse as I’m using it. Now just opening it show just a blank screen.

is anyone going to fix this? my calendar is blank at it’s telling it’s wednesday november 18th. also calendar is completely blank. i can’t believe they didnt push an update right away?

Also refreshing is not right. When looking at tomorrows meetings, and then going back to today it briefly shows my meetings mixed together until I scroll or touch the meetings. It’s really messed up.