Issue with new password

[phd7]

I was trying to update my user password but cant login with the new one. I get no error message when entering the new password.
When changing the 1st pw, I went into the settings/account details/ user manager GUI and entered the new password twice.
Received no error message, just the note "excellent password"

So I rebooted a few times and tried logging in with the new pw. I received no error messages. Instead the login screen simply disappeared and reappeared, looking for a password again. I tried using the old pw and , this time, I did receive an error message stating it was incorrect (rightly so).

In the end , I booted into recovery mode, dropped to root shell, used the old pw as root , and changed my user pw back to what it was and rebooted
This time I was able to login straight away

Any idea why I couldnt use the new pw? Is there a rule I was breaking like max password length, which was not flagged when changing the password?

thanks in advance

[rene]

You likely use home directory encryption. Although everything should be fine when using the GUI tools to change your user password, indeed you'd experience that which you describe if you'd for example change your user password as root rather than as said user. MATE? If so, seems like it would be yet another MATE-edition specific Mint bug.

Anycase; changing your user password as your user simply with passwd from a terminal should work, home directory encryption or not and on whichever edition.

[phd7]

Thanks, I will try the CLI.
sorry, I should have mentioned I am on mint 18, KDE, by the way

[rene]

Ah. Don't believe I ever heard of the issue in Mint 18 times. It might be the case that you've contracted some system-specific PAM damage in which case the CLI route will fail in the same way, and in which case I can personally advise little other than a reinstall; no Mint 18 nor KDE here to compare. Also note of course that if you do not use home directory encryption, the issue must be something else entirely.

[linux-rox]

Aside, you know LM18 hits end-of-support this month, right?