Why do calendar entries disappear after iPhone update?

[iMore Question]

Calendar entries disappear after iPhone update

I have just updated my iPad 2 and my iPhone 6 to ios9 but now all my calendar entries - past and future - have disappeared. I have checked that iCloud is set up. What else can I try to get them back as they are very important???

 

[Bigeric23]

Re: Calendar entries disappear after iPhone update

Do you have your calendar set to show the iCloud Calendar? Have you looked on iCloud.com?