Q: Unable to Sync calendar on iPad with iPhone

Greetings rockyfromnm,

Welcome to the Apple Support Communities!

It sounds like after performing a software update, your iCloud calendars are no longer syncing between your iPad and iPhone. If this is the case, I would suggest working through the Troubleshooting on iOS devices section of the attached article to help resolve the issue. 

iCloud: Troubleshooting iCloud Calendar - Apple Support

Have a great day,

Joe