Unable to Save Calendar to Exchange Office 365 in iCal on Yosemite

I had this problem as well and found that deleting the Time Zone Support cache solved the problem:

1. First, make sure that you can see your hard disk in Finder:
   • Open Finder.
   • Go to Preferences.
   • Select the Sidebar tab.
   • Scroll down to the Devices section, and make sure that 'Hard disks' is checked.
2. Open the Finder Window.
3. In the sidebar, select 'Macintosh HD' under Devices.
4. Open Library.
5. Open Caches.
6. You should see a cache for Time Zone Support. I don't remember the exact name of it as I've already deleted mine, but it should be obvious. Delete the cache.

That's all it took for me. I have no idea why something like that would cause communication issues with an Exchange server, but apparently it does. Hope it works for you!

Didn't work for me :/

Hmm, strange. Did your AutoTimeZone cache get recreated? Mine did, but the problem with Calendar items not syncing with the Exchange server did not return for me. I am, however, having a problem with random email messages on an Exchange server not syncing with the Mail app. Very buggy and unreliable (and extremely aggravating!).

The update to Yosemite that will be coming soon (10.10.1) contains some improvements to Exchange compatibility, so hopefully all these issues will be resolved once the OS is updated. I certainly hope so!

I deleted and re-installed by exchange server login to fix Mail, and now Calendar can't save to the Exchange Server. I've checked and rechecked the server settings, user, password etc. All are fine, but it will not connect and sync.

I seem to find several folks complaining about this across various blogs this week. Is there some secret server/port that seems to work with Office365 and Yosemite Calendar?

I have been having the same problem (I think--see below) with Exchange. I tried the fix suggested by wler771 and deleted the time zone plist file. I suspected that this was the root of the problem because (even with Mavericks) I was having strange modifications of my event times. Some events entered while I was in the Eastern time zone for events that were also to be held in the same time zone were later shown to be in some other time zone. The weirdest was Iceland. (No offense to Iceland, which might be weird or not because I have never been there despite many calendar entries to the contrary.)

My problem: Calendar is entirely useless now and the problem seems identical to Basic101 above. When I click to sync with Exchange, I get an endless barrage of error messages saying "Calendar can't save the event [blah blah] to the Exchange server." If I select "Try Again" or "Revert to Server" I get the same pop up error message again (apparently into infinity although technically I never hit the button more than 25 times or so). If I select "Ignore" all is good---for a while. Then the software tries to sync again and I have to go through the same thing again. I have events in my Exchange calendar that go back to 2009. It was like a Denial Of Service attack on my computer.

This is not my first bout with Calendar. Calendar is the weakest app of all the apps that I use. Even when it sorta worked. Now I have to set all appointments on my phone even when sitting at my desk. That is convenient.

I had this same issue, not with Office365 but another hosted provider, Godaddy hosted Exchange. It turned out that there were some restrictions for EWS in their hosted environment. I called them and they were able to resolve it. Afterwards everything synced fine.

Thanks for this, but it didn't work for me either.

I should warn you that when I deleted the plist file my rules, signatures, and other settings were zapped in Mail. <sadface>

I have run into this iCal problem in the past week and have been trolling fruitlessly for answers to this issue.

I have two dozen computers under management. Some are MacBooks, some iMac. Most are on Mavericks, some using Yosemite. Only one person is having an issue with her calendar.

She's actually the longest tenured salesperson and knows little about managing files on her computer. A few months ago, she ran into an issue where her Mac mail would not load new email, but her iPhone and iPad continued to work. My discovery was that she had 18,000 emails in her inbox. I reduced that number to just 5,000 and was able to fix the problem. (and set up a system of folders for archiving!)

Now she is having an issue with her iCal. I suspect that she has the same issue. With seven years of Calendar dates, she very likely has way, way more than average events saved into her calendars. Before I start deleting her history, I am wondering if anyone thinks this could be an issue with their calendars? I've deleted cache(s) and preferences, but continue running into the problem with this single user. ...thinking volume is the issue....

Thoughts?

My Exchange is hosted and they verified that nothing was wrong on their end. However, they noted that I have WAY more email and calendar entries that other users and that if I were to delete the entries it might solve the problem.

So I have a calendar program that can't keep more than a 16-year-old's worth of calendar entries for it to work right? (Not Exchange. It is working fine so long as I use the OWA interface to the server or my Blackberry.) I guess that makes sense, because that is who their programmers are. However iCal is DOA for me. Busy Cal, however, works just fine (same exchange server and number of entries). My trial is just about up so I have to decide whether to give up on iCal and pay the $50 for something that should (and used to) work with the native OS application.

So my conclusion is that iCal is a smoke and mirrors application under Yosemite. It looks like a real program, but it does not really work.

<Edited by Host>

Did you ever find a fix for this?