After a password hash import and before a successful login, if an imported user inputs the wrong credentials, Auth0 returns the following error on the tenant logs.

Password change required.

The expected error was:

Wrong username or password. 

This article explains this behavior. 

• Password Hash Import

Auth0 rehashes the passwords after a successful login. Before this happens, Auth0 cannot confirm if the login failed because of wrong credentials or an incorrect password hash.