Unable to sync Calendar App after iOS 18 update

Turns out, issue with my calendar was two-fold ... iOS upgrade AND I hit the 50,000 maximum allowable calendar entries in iCloud. Be forewarned that you can unwittingly hit the max and then everything stops working.

Unfortunately, there's no way to back up and delete by date. Only options are to delete item-by-item OR an entire calendar which I could never do because I'm so reliant upon the ones I already have. It's a definite shortcoming of Apple's.

I have to wonder what 'calendar' iTunes is saying it is syncing to on my pc, as, obviously, it's not working!

You have no idea how badly I wanted your solution to work for me! Sadly, I must report it did not. Here is my longwinded reply. Let me first say that both my iPhone and my iPad use the EXACT same settings with the only difference being the OS versions. iPhone does not work for calendar - works for Contacts; iPad works for both Contacts and Calendar.

Here are the accounts that I have:

My main account is the Destcom, which is my work account. The Gmail is my personal account that I only use for email and nothing else. The others are the same, email only. The iCloud I use for nothing related to email, contacts, or calendar.

My gmail account shows me this, and note the options. Showing this just to show the options for contacts and calendar are toggled off:

This is my main account; you will see there are NO options to toggle contacts or calendar:

However, for more years than I can remember, I've always synchronized my contacts and calendar through iTunes, and this is the setup I've had forever:

There is an obvious connection between iTunes and Outlook since all my contacts update correctly. Without reverting my phone back to 18.1.1, I can only assume this might be an OS version issue. I might possibly try doing this very thing this weekend, but it's always a pain to me when I've had no issues up until OS18.

Glad yours is working again! Now, for those of us who don't use iCloud for calendar, but rather syncing to Outlook with iTunes, waiting for something to happen positively again! :-D

I use google calendar for work and 2 businesses. Since the IOS 18 update, my entire Google Calendar has gone blank. I am beyond lost and ready to explode 🤬🤬🤬

Thanks for mentioning this. I sync the same way. But, I dont show any "verify account" at the top of my calendar list. Which ios version are you using? I am at 18.0.

FYI the tip to fix does work but you have to really patient to let it re-sync. I did it twice because I wasn't being so patient :)

For those of us on this thread having the inability to sync the iPhone or iPad using iOS18 to Outlook through iTunes, I can only surmise that Apple, even though I've seen no comment from them on this thread, has phased out the Calendar function.

I had iCloud for windows on my PC already, but when I flipped the switch to sync Contacts and Calendar items to Outlook, it errored out saying I had no default profile. This was untrue.

SO, Here is what I did to make sure I lost nothing in the process:

On the iphone, I first switched on the Contacts and Calendar items to go to the iCloud. This would insure that all my stuff was synced to the server before moving on.

I made a backup of my Outlook data to a backup.pst file

I had to completely delete iCloud for Windows. Then rebooted.

Ran the setup for iCloud for Windows, and it went through the entire process of setting everything up, from Photos, to Files, etc. When it got to the Outlook portion, it took a couple of minutes to do it's thing, but was thankful I began the process on my iPhone first.

Once this was done, I lost nothing, but I will miss the ability to use iTunes and not be relying on a 'cloud connection'.

There is an alternitive to iTunes that will cost you $40 if you google "Programs to sync iPhone with Outlook"

Me, too! I have a “New” iPhone 13 which is not even a year old and …

Apple Customer Support actually misinformed me by instructing me to do a Software Update 18.0.1 and DID NOT warn me that I would loose my CONTACTS and my CALENDAR.

Now, I desperately need Apple Customer Support which appears to be non-existent to recover my CONTACTS and my CALENDAR.

I DID have success with contacts, finally. From settings / contacts / contact accounts / exchange, uncheck contacts. Then force a reset of the phone and when it comes back online navigate back to the same place and re-check contacts. THEN on the contacts settings scroll down and change default account to exchange. Now when you go to contacts / lists you should see exchange and your contacts populating. I’ve got 3300 contacts it was fun to watch the number of contacts grow until it was done and now I’m ok. While the calendar issue is SO frustrating and apple support acts like I am the only one with the issue, It just has to be an ios18 issue and fingers crossed it will get resolved with the new AI update at the end of the month.

I had the same problem after having to get a replacement phone (and update to ios 18). I just solved it by going to the calendar on my phone, clicking on "calendars" and at the top of the list of calendars was a "verify account" line. I clicked on that, and it was all I had to do. Went back to my PC and hit refresh, and I found it immediately matched my phone.

Hope this helps!

My calendar is having similar issues. (IOS 18.0.1 Iphone 16)

I turn it on, and it doesn't even know what day it is. It thinks it is October 1 when it is really November 10.

I add an event to my calendar, and it does not appear. But when I search for it, it comes up in the search.

When I delete an event and "all future events", it deletes past events as well.

It is behaving as though my calendar does not know what day it is. I click on a day with a colored dot, and it does not show me what is there.

This phone is brand new, and not being able to use my calendar to reliably track my appointments is crippling.

Similar issue with everyone here.

Have been syncing my Outlook contacts and calendar from my Windows PC to my iPhone successfully for years.

Updated to iOS 18.1 and can no longer sync even after unchecking SYNC CALENDARS, checking it, and overriding iPhone several times.

Simply does NOT sync any more.

Has ANYONE had any success with this?

Extremely disappointing : all my events are" misplaced repeating events show = sign everywhere : I mean I did this upgrade accidentally I REGRET SO BADLY. THE CALENDAR IS NOT A BONUS. It's essential , your product is NOT ESSENTIAL IT's a luxary . I DON'T understand why your so careless with customers : Would it be pic app / game app / I can understand , but the calendar , to wake up and see this mess after over 15 years of impeccable service and us counting on you for the price we pay : DONT DO AN UPGRADE so soon . We can wait. And do your job as we try to do ours! As this calendar issue is gonna be costy at least for me.

Same issue here; Exchange no longer syncs. Could this have something to do with higher security settings in 18.1? I noticed when I try adding a new Exchange account a message appears saying that “your Exchange administrator will have access to your device and the ability to delete data from your phone.” Could it be that I have a security settings turned on that’s blocking the Exchange account?