User Mailbox (Hybrid/On-Prem) Failing with "Failed to initialize MAPI subsystem"

Last post 12-04-2020, 6:26 PM by BBeenn. 2 replies.
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  • User Mailbox (Hybrid/On-Prem) Failing with "Failed to initialize MAPI subsystem"
    Posted: 12-04-2020, 2:22 PM

    Hi there,

    I've been having an issue with the User Mailbox Backups. My environment is a Hybrid setup with the majority of mailboxes on prem. Everything was working fine until about 2 months ago. Went through CV support but they have been completely useless and are blaming it on microsoft at this point.

    Exchange Server is 2016 running on Windows Server 2016.

    Access node is server 2016 running Outlook 2013 SP1


    The few exchange online mailboxes that we have backup without issue.  


    Any on prem mailboxes fail with error:

    ExAgentController::SetFatalError() - Agent [] Worker [0] reported fatal error [469762432 : Failed to initialize MAPI subsystem. Please verify that Outlook is installed and matches the bit width of the software. If Outlook is installed, try the following: 1) Reboot the machine, 2) If using a static profile, delete it and recreate it, 3) Reinstall Outlook], stop the controller

    Every other operation in both CVMailBackupCoordinator.log and CVMailBackup.log appear to run successfully.

    I can't find anything online. I've tried all of the troubleshooting steps in CV's documentation.

    Tried everything here: 

    Gone through the service account setup several times. Reinstalled different versions of outlook over and over, static profiles, changed access node server. Nothing works

    Readiness Check on the Mailbox client passes with all options selected. 

    CV is currently on 11.20.22 as I was told this would probably fix my issue.

    Any info would be greatly appreciated. I am tearing my hair out over this one. Please let me know if anymore info is needed.



  • Re: User Mailbox (Hybrid/On-Prem) Failing with "Failed to initialize MAPI subsystem"
    Posted: 12-04-2020, 5:40 PM

    Hi Ben,The similar issue was addressed in HFpack 24, currently HFpack 27 is available for download.

    Can you please isntall and it should get resolve this issue.


    if you see any other issue pleas erespond back.


  • Re: User Mailbox (Hybrid/On-Prem) Failing with "Failed to initialize MAPI subsystem"
    Posted: 12-04-2020, 6:26 PM

    Oh my sweet god, it looks like its working.

    I could kiss you.

    Thank you so much. 


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