Unified Messaging Exchange server 2016 issue...

Brad Campbell 31 Reputation points

Unified Messaging can't validate or generate a UM PIN for mailbox 'mailbox@keyman .com' : An error occurred
while accessing the user's mailbox. Details: The underlying connection was closed: An unexpected error occurred on a

This issue started recently not exactly sure when. We are running Exchange 2016 CU18

I cannot view the UM details for any UM enabled user in EAC. I also cannot enable or disable UM for any user.

Exchange Server Management
Exchange Server Management
Exchange Server: A family of Microsoft client/server messaging and collaboration software.Management: The act or process of organizing, handling, directing or controlling something.
7,387 questions
0 comments No comments
{count} votes

Accepted answer
  1. Andy David - MVP 142.7K Reputation points MVP

    Did anyone mess with the TLS settings on the Exchange Servers?

3 additional answers

Sort by: Most helpful
  1. Lucas Liu-MSFT 6,161 Reputation points

    Hi @Anonymous ,
    Have you made any changes to related settings recently?
    1.Please check to see if “SystemMailbox{e0dc1c29-89c3-4034-b678-e6c29d823ed9}” exists. According to my understanding, this system mailbox used by Unified Messaging in Exchange 2016 for storing UM console attending files and other information.
    For more information you could refer to: Arbitration mailboxes
    2.Please try to run the following command to check if you could view the detail information of UM:

    Get-UmMailbox -Identity <> | fl  

    3.Please try to run the following command to enable the UM for user:

    Enable-UMMailbox -Identity <> -UMMailboxPolicy <> -Extensions <>  

    In addition, please try to reproduce the issue. When the error occurs, check whether there is a related error log in the Event viewer. If it exists, please share it with us, please pay attention to is to cover your personal privacy information.

    If the response is helpful, please click "Accept Answer" and upvote it.
    Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.

  2. Ashok M 6,506 Reputation points

    Hi @Ivan R ,

    Have you checked the state of the arbitration mailbox? Is it happening to specific mailbox or all mailbox?
    Can you check for events MSExchange Unified Messaging to find out the inner exception?

  3. Ivan R 1 Reputation point

    Problem with all mailboxes.

    0 comments No comments