Sébastien Page, writing for iDownloadBlog, digs into an error that is both common and non-obvious and lays out the fix.

Yesterday I decided to look at when my new iPhone 6s backed up to iCloud for the last time when I realized that it hadn’t actually been backed up since September 25, which coincidentally was the first day I got this new device.

Check out your most recent iCloud backup. If those automatic backups have not been keeping up with the times, then this article is for you. Either way, this is worth bookmarking (for future reference) and passing along.