I suddenly cannot backup to iCloud from iPhone and iPad

I have the same problem as you! Glad to see I’m not alone my last successful backup was November 18. iOS 18.1.1 and iPadOS must’ve be the culprit. Same issue of heading back up now but after a few seconds, it just says it can’t be completed. Also I have plenty of iCloud storage as I pay for it.

Hello~ Absent of a forced restart …can’t think of anything else except contacting Apple Support. Go to lower left and click on the small Support icon or…

Contact Apple for support and service - Apple Support

~Katana-San~

I'm on the phone right now and guess the issue is pretty new, so they're unaware. The person seems to think that iCloud backs up the whole device (50GB) when iCloud backups aren't always the entire device. My says the backup size is 1.8 GB. What did they have you do?

Thanks for the update sorry it’s my first time here and I find people posts go all over the place. I have a call back tonight so I’m waiting cause they had me submit a bunch of info for troubleshooting and don’t want to mess anything up for the techs. It’s so scary to delete your backup when you don’t know if it’s going backup lol

For me just reinstating the option to backup didn’t work. I was able to go into iCloud backup on my iPhone and iPad delete the backups and then I turned backup on again and it made a new backup without any error. I only have my current backup but that is fine with me. I was so worried that it was going to be weeks without one. Appreciate your help it was more helpful than the advisor I had. :)

Hello~ Click on below and review…

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

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

~Katana-San~

Hello~ Have you restarted your iPhone?

Force restart iPhone - Apple Support

Are you using a VPN? Are you connected to WiFi? Try a different cable?

~Katana-San~