Why does backing up to iCloud get stuck?

Nonowt wrote:

Backing up gets stuck at “time remaining”. Running 18.4.1 on iPhone 16 pro max.

This is common if it is your first time backing up to the cloud.

Is your phone connected to a power source, locked and left alone so it can back up?

Nonowt wrote:

It’s not the first time. Set to auto back up and last time two weeks ago. Yes left.

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