I was given the Apple alert to update to the new iOS 13 today. I did my backup manually, then did it.
1/2 way through, it stalls. iTunes says to try again. Did so 3 times, tried new cables, direct cables rather than through hub etc. Nope. Failed. iTunes then tells me the phone cannot be updated and must be restored.
It's still doing the restore backup from iCloud now. It had BETTER work or I go back to Android
Just for giggles, and to see I was not crazy, I tried updating my daughters iPhone SE (mine is an SE too), on a different computer using a brand new, never opened cable. SAME THING.
13 is an unlucky number for iOS it seems. So, wait a couple days and see if Apple patches this one.