Calender duplicates multiple times and disappears within seconds on IPhone

New Contributor

We switched from Exchange 2016 on premise to Office365 Business Premium.

So far everything works fine except of one IPhone (Iphone 8, latest updates installed).


The Office365 Account is added as Exchange Account to the IPhone and after one day of working fine the whole calender duplicates multiple times (up to 18) and then completly disappears. Everything is happening within seconds and all day long. Only way to stop is to remove the account. 


We removed the account and readded it - same result. After one day the calender goes crazy. Nothing else is affected (Mails, Contacts,..).

Calenders are not duplicating on the server or pc, it´s only on this one IPhone.


Anyone has an idea?


1 Reply

I found out that someone gave all employees full access to this one calendar (read / write / delete). After changing the settings to just read the details everything seems to be fine.

will report later if everything stays fine.