Consider the following scenario:
Your mailbox is on a server that's running Microsoft Exchange Server 2016.
You log in to Outlook on the web (Outlook Web App).
You try to change your password.
In this scenario, you receive the following error message:
The requested search root's domain 'childDomain.contoso.com' is different from the scope root's domain 'contoso.com'.
To resolve this issue, apply Cumulative Update 6 for Exchange Server 2016.