Took the plunge and updated my iPhone 5s from iOS 10.6 to 11.4.1, via wifi (couldn't do it via iTunes as it wanted iTunes 12.7, I'm using 12.6). Before the update I backed up the phone to the Mac using iTunes/USB cable.
Following the update, no problems with new iOS.
I wanted to do a backup to the Mac of the new installation. After a few minutes I get dialog "iTunes could not back up the phone "chuck's iPhone" because an error occurred."
Bummer. Rebooted both the phone and the Mac, tried again. No Joy. Suggestions?
Chuck, I'm guessing that because it needed iTunes 12.7 to install, it also needs it to backup. It should be able to backup to iCloud.
FWIW, I've been using iMazing lately to manage my various iPods and iPads. Works with everything from my iPad Air 2 running the latest iOS 12 public beta to my original iPad.
"I really need a new tagline"
—P M Evans
I installed iTunes 12.8 (current version), to see if that was the case, but to no effect.
My pre-research had indicated that 12.6 was supposed to still be OK for managing iOS 11.4 devices and for Apps. Noting the stupid loss of ability to manage apps from the computer. I got an eval version of iMazing a while back, like it. May have to make the purchase.
A follow up to the above...
I was recently getting nag messages on my AppleTV (3rd Gen) that I needed to re-log into iCloud and App Store from that device. I don't use any iCloud services with the AppleTV so I had ignored the nags. The other night I decided to log back into iCloud from the AppleTV.
After doing so, all my other Apple devices asked for verification and a 6-digit code was sent to my iPhone. After doing this on the Mac, iPad Air2 and iPhone 5s (the one giving me fits), I tried the backup from the iPhone to the Mac via iTunes. This time it worked, no mysterious Error message. I don't get why an iCloud action involving AppleTV should affect a USB iTunes backup process, but apparently it did. More "hide and seek" discoveries courtesy of Apple, I guess.