macOS – Fixing Terminal Error When Typing Passwd *Username*

The problem you are encountering is that when you run su by itself, you are not entering a 'login' shell. This means that your environment, working directory, and everything except uid/gid remain the same of the original user.

Login triggers do not execute, and you experience the issues you describe.

A simple solution to a simple problem:

su -

From the su(1) man page:

The su command is used to become another user during a login session. Invoked without a username, su defaults to becoming the superuser. The optional argument - may be used to provide an environment similar to what the user would expect had the user logged in directly.

Also:

   -, -l, --login
       Provide an environment similar to what the user would expect had the user logged in directly.

If you su into a login shell, bash will behave as you expect, and automatically source the appropriate files on "login", without the need for overly hacky workarounds.

I got this message too and solved it easily:

Go to System Preferences; Users and Groups; Select the Admin User and click the padlock to make changes; enter the Admin's password; Click on the picture of the Admin; the word 'edit' should appear; Select Camera; Take a new picture of yourself and save it; Lock the padlock again; Restart the computer. You could probably take a different option instead of 'Camera' but I didn't try that.