In the Microsoft Exchange Server 2016 or Exchange Server 2019 environment that has multiple domains, you can’t preview search results of an eDiscovery search in Exchange admin center (EAC). Additionally, you receive the following error message:
Unable to display mailboxes
fix this issue, install one of the following updates:
For Exchange Server 2019, install the Cumulative Update 2 for Exchange Server 2019 or a later cumulative update for Exchange Server 2019.
For Exchange Server 2016, install the Cumulative Update 13 for Exchange Server 2016 or a later cumulative update for Exchange Server 2016.
Learn about the terminology that Microsoft uses to describe software updates.