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After the December 2023 update, I have the following error in outlook 2021: "Unable to start Microsoft Outllok. Unable to open the Outlook window."

Sr2_1 0 Reputation points
2023-12-13T18:29:35.3633333+00:00

The operating system is updated when you restart the outlook stops working. When you open Outlook, the following message appears:

Microsoft Outlook.Cannot start Microsoft Outlook. Cannot open Outlook window. Cannot open the set of folders. The attempt to log in to Microsoft Exchange failed.

Use the following methods to try to resolve the issue, with none of them working: Recover the Navigation Pane configuration file Repair Outlook files Start Outlook in Safe Mode Use SetupProd_OutCon Check that the. OST Was Not Write-Protected

Use Exchange server 2019 and Office 2021, updated on December 13. Last Updated KB5033375 Windowns 11, version 22H2

Outlook | Windows | Classic Outlook for Windows | For business
Windows for business | Windows Client for IT Pros | User experience | Other

4 answers

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  1. Hal Hostetler MVP-Outlook 521 Reputation points MVP Volunteer Moderator
    2023-12-24T15:16:50.74+00:00

    Virtually every time I've seen that error response, it was due to a corrupt Outlook Profile, please see:

    Adding/Recreating a Mail Profile

    1 person found this answer helpful.
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  2. S.Sengupta 24,716 Reputation points MVP
    2023-12-14T01:08:42.4033333+00:00

    Kindly go through the following Microsoft reference article:

    Fixes or workarounds for recent issues in Outlook for PC

    0 comments
  3. SokiGuo-MSFT 31,541 Reputation points Microsoft External Staff
    2023-12-14T08:00:50.52+00:00

    Hi @Sr2_1

    Welcome to our forum!

    I agree with S.Sengupta. You can try the steps in the above article to fix this issue.

    Also, based on my search, you can try the fixes mentioned in this document: I can’t start Microsoft Outlook or receive the error “Cannot start Microsoft Outlook. Cannot open the Outlook Window” - Microsoft Support.

    User's image

    If it doesn't work, to better troubleshoot this issue, I would like to ask the following questions to get some more information:

    1. Does this issue occur on domain-joined devices or devices outside the AD domain?
    2. Have you done some changes before this issue occurs?

    Hope this helps!

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  4. Sr2_1 0 Reputation points
    2023-12-29T14:02:22.0733333+00:00

    Hello.

    The account is from Microsoft and this is an on-site server with Exchange 2019 on windows server 2022.

    If you check the PDF I sent you, the only way I can get the email working again is to remove the perfl.

    For now it's just working like this, deleting the profile every day and recreating the OST.

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