My Galaxy S6 gave me a error message today. " Unfortunately, Calendar has stopped.

[AC Question]

Hi, Put an enty into my calendar, hit save and got the message. I sync with Microsoft Exchange and had problems until the migratetion to Office 365 was complete. Calendar was working for 1 month great until now. Tried rebooting, removing the account and reinstalling. Ii goes throuh the sync process and when its done putting all the entries back in a get the message. Can't open calendar at all.
Thanks, Vinny