Calendar freezes on iOS 18

The hang/CPU utilization was so bad for me I’ve been unable to remove the Exchange account. Charging also stopped due to overheating. Calendar even hung when simply tapping OK to acknowledge notification of an expected appointment.

Happy to report I just updated my iPhone 15 Pro Max to iOS 18.1 and 13" iPad M4 to iPadOS 18.1. Full disclosure I only tried adding a few test events to our family shared iCloud calendar on each device and modifying a few existing events but so far no freezes. Hope to see that the battery drain issue with increased calendar activity in the background has resolved too and will report back when I have enough data.

Confirming calendar background activity no longer listed under battery usage by app and excessive battery drain and abnormally increased temperature have resolved on both my iPad & iPhone. Only casualty, other than losing significant utility from devices from iOS 18 till 18.1 and time wasted trying multiple failed interventions to correct issue by myself and with the assistance of regular and upper tier customer support, is a permanent drop in my iPhone 15 Pro Max battery from 100 to 96% maximum capacity.

For me, I determined it was my Exchange account that was causing the issue (my employer recently changed their security rules and doesn't allow Apple apps like Calendar to pull data). I couldn't even delete the Exchange account (Apps -> Mail -> Mail Accounts) - it showed up gray and unauthorized and didn't do anything when I tried to delete it. I had to go into accounts (Apps -> Mail -> Mail Accounts) and change the Fetch New Data on the Exchange account from Push to Fetch. This let me delete the Exchange account and that fixed the problem. It seems the Calendar was stuck in a mode of trying to continuously Push communicate with my Exchange account but not getting the response it needed, so it froze my calendar and killed my battery through background utilization. I now have to use Outlook (and its calendar and contacts) instead of the Apple version for my Exchange data (not ideal, as I did like having everything on one calendar). Good luck!

Same here! Just installed 18.1. and my iPhone 14 Pro Calendar App connected with exchange Account seems to work again.

i´ve tested a few events, edited and it everything synchronize.

Thank you  Team! ;-)

FYI see the following thread same issue: iOS 18 makes the calendar «freeze» - Apple Community. A member was able to fix the calendar freezing issue by resting the iPad and setting up "from scratch". Have asked for clarification but when you did your restore did you then use a backup from iCloud? Assuming if database was corrupted then indeed may need to start completely over but don't want to go through all this work if will still fail especially if does get fixed in an update.

Just installed iOS 18.0.1 but the issue remains.

Reposted from: iOS 18 makes the calendar «freeze» - Apple Community

Steve you are the man!!! Took my exchange account off on both my iPhone 15 Pro Max and 13" iPad Pro M4 rebooted and normal calendar function. Then readded exchange account and still normal calendar function. Hope battery function will normalize will report back if it does not.

Thank you!

Short lived victory. iPhone shared family calendar still functioning normally but crashing again on iPad when try to add event.

FWIW I had these same issues on my iPhone and iPad. 18.1 fixed it for me. Your device will eat a bunch of battery repopulating your calendar, but then returns to more typical usage patterns.

Wasn’t making any assumptions particularly with the wording of the person who had a successful solution to the issue doing a reset and then “starting from scratch” in the additional stream I referenced. Just gathering data. Thanks for clarifying.

same issue on my iPhone 14 pro /iOS 18.0.1.

When I connect the exchange Account the calendar app freeze and drain Battery. After disconnect everything works.

On my iPad mini iOS 15.8.3 and on my Mac Ventura 13.7. all accounts, including exchange, are connected and work fine (Mail,Contacts,Calendar,).

Hope Apple will fix it with the next iOS update.

Ditto (except my issue is on an iPhone 14). I hope a patch gets pushed out quickly.

Reset did nothing for me, other than force me to retrain my iPhone how I like things.