My MacBook Pro is running Sierra with FileVault enabled.
I recently enabled iCloud 2 factor authentication. I had previously been using 2 factor verification, and my macOS account password was linked to my iCloud password.
When I moved to 2 factor authentication it asked me to create a new password for my macOS account (maybe you can't link your macOS account password to your iCloud password anymore…)
Now that I changed my password, I had trouble logging into my machine so I had to use the password reset feature on the login screen (it rebooted into a recovery mode and I had to put in my iCloud password so that I could update my local user's password).
I updated my password again thinking I had mistyped it, and had the same trouble.
When I booted into the password change recovery mode again I noticed a message in the change password dialog box that said that you might have trouble logging in if your password has punctuation or accented characters.
Sure enough, removing these characters from my password allowed me to log in.
Does anybody know why this limitation exists? I don't know if it has to do with FileVault or what, but I can't find any information about this limitation, and I've had symbols in my passwords for years on OS X when I wasn't using FileVault.