I've been having a problem with passwords since installing sierra on my mid 2011 mac mini. Several times now, I've had to reset my password (via terminal while booted into recovery mode) after waking from sleep to find my existing password not working. When I wake from sleep, I'm prompted for my password (system shows my user name and account picture). I enter the password to no avail. If I then restart the system, I'm prompted for both a username and a password (no account picture shown). Again, unable to login. I haven't been able to find any mention of this issue online. I tried making a new keychain this afternoon - that might've triggered this most recent lock-out episode. Otherwise, I've been unable to correlate this phenomenon with anything concrete. I will add that I did a manual migration, which wasn't the most elegant process ever. Not sure if that matters, but I thought I'd mention it. Thanks!