I just ran into this with a seldom used MacBook Pro 2016/2017. I couldn't reset the password via iCloud and eventually I realized the system clock was wrong (on

I just ran into this with a seldom used MacBook Pro 2016/2017. I couldn't reset the password via iCloud and eventually I realized the system clock was wrong (on the order of years). I had to boot into the OS X recovery mode and start a terminal and set the date and time by the command line. Of course, none of the login screens have a time/date setting widget let alone show the system time and date so it took a bit of guessing. Once the system time and date was correct, the iCloud password reset feature worked without issue.