ERROR_PASSWORD_MUST_CHANGE implies, on Microsoft Active Directory, that the Entry's password must be changed before logging on LDAP pwd-Last-Set attribute: value of 0 indicates admin-required password change - MUST_CHANGE_PASSWD

The key code in the string is the Hex Value "1907" which is referenced in the Microsoft Response Code

Returns only when presented with valid username and password/credential.

More Information#

There might be more information for this subject on one of the following: