Consider the following scenario:

  • You have installed Microsoft Exchange Server 2019 Cumulative Update 9 (CU9) or Microsoft Exchange Server 2016 Cumulative Update 20 (CU20).

  • You add a mailbox-enabled user to the "Recipient Management" role group, or you assign the "Mail Recipient Creation" role to the user.

  • You log in to Exchange Admin Center (EAC) as this user.

  • Under Recipients > Mailboxes, you select the plus sign, and then you select that user's mailbox.

In this scenario, you receive a "500 - Unexpected Error" error message, and you don't see an option to create a new mailbox.


To fix this issue, install the following cumulative update, as appropriate:

Cumulative Update 10 for Exchange Server 2019 or a later cumulative update for Exchange Server 2019

Cumulative Update 21 for Exchange Server 2016 or a later cumulative update for Exchange Server 2016.


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

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