unable to update my ipad cloud

Some people have posted they had to let it run overnight for the update to complete.

Some other things you can try. Do you have access to another WiFi network where you can try? That has worked for several people.

Try a restart.

Restart your iPhone, iPad, or iPod touch         

Try a forced restart.

Reset Device.      

If necessary

Hard reset.        

Do a backup and try a factory reset. Then restore from your backup.

Restore to Factory setting.      

Backup - Restore your device from an iCloud or iTunes backup.      

See If you see an error when you update or restore your iPhone, iPad, or iPod https://support.apple.com/en-us/HT201210  and

iOS update and restore errors https://support.apple.com/en-us/HT204770

When you say you "Recently changed my Apple ID", did you change your existing Apple ID, or did you simply create a new Apple ID?

If you create a new Apple ID, there is no way for any of Apple's systems to "know" you are the same individual as any other Apple ID.

Therefore, if you succeed at changing what Apple ID your devices use, your former iCloud storage will no longer be accessible, to you. (Until corrected.)

IOS update or some other type of update? Are you trying to get more iCloud storage? More information would help.

Buy more iCloud storage.    

When changing to the new ID, there may be some data loss, but you can minimize it. If syncing photos with iCloud, ensure Optimization is turned off in Settings/Your Name/iCloud/Photos and/or in Photos/Preferences/iCloud. Then make sure full resolution photos are on the device/computer. When signing out of iCloud, if asked whether you want to retain data, choose yes. Messages conversations will be lost if they are addressed to the ID. See the article below for other places that the old ID should be removed. See Winston Churchill's response in the below discussion. If possible, also set up Family Sharing  between the IDs to keep access to your apps/purchases. 

 How to switch Apple IDs on your iPhone or iPad.      

How to transfer all files from one iCloud account to another.       

What to do after you change your Apple ID or password - Apple Support.      

Family Sharing.         

Family Sharing - Set up.        

For iCloud, Nalaowner, your ID is your Apple ID.

Are you trying to update your Apple ID, or are you trying to change what Apple ID you are using for iCloud access?

Nalaowner:

Please check out the following, and let us know if any of that helps!

What to do after you change your Apple ID or password - Apple Support