I encounter the same problem forum user BDK mentioned elsewhere in this forum, only I encounter it on my iPad 2:
CalDav sync no longer works after ios5 update on iphone 4
My calendar associated with my caldav account is no longer even visible in Calendar even though all of the account data is intact on my iphone and all seems as it was. In Calendar I can only see iCloud and Outlook, but the CalDav calendar is just gone. All my appointments are missing obviously - anyone have any thoughts on how to recover? This is with ios5 as released on 12 October 2011.Me too I would like a solution for this otherwise I won't be able to upgrade to iOS5 on my iPhone 4.
thanks for any help.
Thanks for a lead in the good direction.