iCal not syncing with Exchange calender in OS X 10.10.2

I went through all the steps in this thread, and was not able to resolve. I then went through MS and Apple support which led me to create a new Yosemite Partition with a whole new OS. The behavior reproduced.

Finally, I switched Outlook to list mode sorted by date on a Win10 PC. I had calendar events in the 1600s! I deleted these and everything started working again. I thought I'd circle back and post it here to help others. It may not be the cause of everyone's problems, but it helped me.

Here is my solution: After deleting the Calendar caches as explained earlier it was still not Synching properly. Then I deleted all my Calendar items from the exchange account. I use for this Outlook for Mac, but you can probably use anything, just be sure to delete EVERYTHING from the calendar. It is now synchronizing perfectly between Mac Calendar, Outlook for Mac 2016, iPhone, etc. A little note: before deleting every Calendar item, I did an .OLM export. Unfortunately when I restore it back, it was missing a lot of appointment. I strongly suggest before the deletion, to export them one by one as .ICS files and or manually write them down somewhere. My best guess is that somewhere in the Calendar Exchange database there were a corrupted item, infact the OLM export-import will not work properly. I hope it helps Cheers

It helped me too. Initially it did not work, but stopping "CalendarAgent" made it work. Thanks!!

Thanks Wayan, this helped with clearing the calendars that failed to delete on iCal for OS Sierra Beta 7, However the. problem calendars did return after. 2 minutes. when iCal was restarted.

Note to all. The mentioned. Library and Calendar folder for this fix. are hidden system folders.

Finally managed to fix it.

Ended up signing out of iCloud on my iPhone and deleted all iCloud data from my iPhone.

I then re-deleted the cache files for the calendars in the Calendars folder in Library.

After that I logged onto iCloud directly and made sure was deleted there as well.

Following that, I dragged the recurred. calendars from iCloud to the. on Mac. section in iCal. managed to delete.

Has not returned! Problem solved.

Persistence pays off!

Hi

Just tried deleting the calendar cache - now i have no dates in my diary - and I'm a little stressed!?!

ok - delete last message - I switched it all off and on again and my diary is back - phew!! and exchange works ! cheers

I used this solution and it helped. Exchange is now syncing with my calendar again. However, i lost all my delegate calendars and cannot add them again as the Calendar app continues to update the delegate list but without result. It is stuck somewhere in the process. Deleting and reinstalling the exchange account helps. I can reconfigure the delegate calendars but then after a few days i encounter the same syncing problems again. So the process starts from square one again, with clearing cache and loosing the delegates. Any solutions? Apple support blames Exchange but this is clearly an issue in the calendar app.

I had a similar problem using Sierra OS X 10.12.1

My issue was resolved by:

1. Closing Calendar

2. pkill CalendarAgent # From a terminal

3. Opening Calendar

Other things I tried that didn't work in this case:

1. Remove/readd Calendar from the Exchange Account in Internet Accounts

2. Restarting Calendar

3. Removing the timezone cache file under /Library/Caches