icloud backup not working

Did you update to iOS 16.3?

do you use 2FA?

Are you trying to turn on iCloud backups and getting an error message?

If none of this apply to you, see this for some help.

If you can't back up to iCloud - Apple Support

I have over 45 GB available on my phone

See -> What's the difference between device storage and iCloud storage?

What's the difference between device storage and iCloud storage? - Apple Support

Check which iCloud subscription do you have.

Go to -> Settings -> your name -> iCloud -> if you see 50 GB (or 200 GB or 2 TB) then you have an iCloud subscription.

If you have an iCloud subscription, you will receive a monthly bill from Apple, check your email box.

You pay monthly for iCloud storage.

iPhone 11 Pro

iPhone 11 Pro has three internal storage options: 64 GB, 256 GB, and 512 GB.

Check which iPhone 11 Pro do you have.

If you have an iPhone 11 Pro with 256 GB or 512 GB, you need to have 2 TB iCloud subscription.

See the following Apple articles:

How to back up your iPhone, iPad, and iPod touch

How to back up your iPhone, iPad, and iPod touch - Apple Support

Backup methods for iPhone, iPad, and iPod touch

Backup methods for iPhone, iPad, and iPod touch - Apple Support

Upgrade to iCloud+ -> Upgrade to iCloud+ - Apple Support

If you back up the iPhone to your computer you will need space too.

How much space do you have available in iCloud? Go to Settings, tap on your name, then iCloud to find out.