I upgraded the software on my iPhone and my Yahoo Calendar stopped syncing via CalDav I recently updated my iPhone to IOS 5.0.  I was syncing my iPhone calendar with my Yahoo Calendar using CalDav.  After the upgrade the syncing stopped working.  I tried deleting the calendar sync profile and re-adding it, but when I get to the step where it verifies the settings, it fails.  What can I do to fix it?
Here's what I did to fix the problem.  I got the answer from this forum post.


Delete CalDav Yahoo calendar sync profile in the iPhone settings.
Go to Safari settings and click Clear History and Clear Cookies and Data.
Turn iPhone off.
Turn iPhone on.
Re-add you Yahoo Calendar CalDav account.


To re-add your Yahoo Calendar CalDav account:


Go to Settings
Click Mail Contacts, Calendars
Click Add Account Option
Click Other
Click Add CalDAV Account
Server: https://caldav.calendar.yahoo.com
Enter you Yahoo user name and password.
Click Save.