This pop up disabled below made me to debug for quite a long hours.
This is an initial level of security feature enabled by your hosting provider for their host. By default this basic screening will be skipped off. However if multiple login failed from the same IP address in specified span of time, this feature gets activated and the users are prompted with this pop up.
Root cause : Multiple instance of login failed during the specified span of time from the same IP. Manual Change of credentials in wp-config (php file). Improper sync / change of respective database.
Fix ( Either of the below mentioned fix can work, depending on their use case): Repair your database from your Cpanel. Contact your hosting provider for user id and password of initial screening explaining the use case. Roll back your wp-config (php file) from backup.