No room lists found when trying to add a room in OWA in Exchange Server 2019 or 2016 (KB5006992)

Symptoms

In Microsoft Exchange Server 2019 or 2016, you have the following users:

• User1 has a remote mailbox that's migrated from on-premises to the cloud.

• SM1 is an on-premises mailbox that acts as a shared mailbox to be used in the cloud (for example, by User1).

In Outlook on the web, User1 accesses the SM1 mailbox by using User1's own credentials through the following URL:

• https://OnPremExchangeServer/owa/SM1@<domain.com>

In this situation, User1 can access everything in the SM1 mailbox, including the Calendar. However, when User1 tries to schedule a meeting, and selects the Add room button on the Location line, OWA returns the following error message:

Resolution

To fix this issue, install one of the following updates:

Cumulative Update 11 for Exchange Server 2019 or a later cumulative update for Exchange Server 2019

Cumulative Update 22 for Exchange Server 2016 or a later cumulative update for Exchange Server 2016

References

Learn about the terminology that Microsoft uses to describe software updates.