Exchange 2016 IMAP Service stopping after installation CU23

Mariusz Gora 41 Reputation points


I installed CU23 for on premise Exchange 2016. After installation every IMAP connection stops IMAP Service.
I try establish IMAP connection via telnet without send any data but it also stops IMAP Service.
I even not see IMAP banner..

In Event Viewer I can see only information service is trying to stop (event id 1002) and then information its stops successfully (event id 1001).
Finally in EV shows " The existing worker process HasExisted value before calling CloseProcess is True" (event id 1040).
There is no errors or warnings in Event Viewer.

Before upgrade everything works fine.

Have you any suggestions?

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.
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  1. Steven GALLUCCIO 10 Reputation points


    In my case, the server was a member of a DAG and was in Maintenance, once out of maintenance mode => no problem to start the IMAP service

    2 people found this answer helpful.
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  2. Amit Singh 4,861 Reputation points

    Is this a multirole server? Check if the front end and backend receive connectors are set to port 25 instead of the backend being port 2525.

    Also, If the IMAP service is broken - Run the following command on a PowerShell window.

    Get-HealthReport <servername> | where { $_.state -eq “Offline”}  

    It will return an offline IMAP.Proxy healthstate.

    Please note that IMAP and POP services are usually not enabled by default and are only done when the decision is made to use them.

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  3. Jiqa 0 Reputation points

    Dear Steven,
    thank You for sharing it! :-) I had the same problem and it helped.

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