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unable to login

Roger Roger 6,921 Reputation points
2025-02-13T22:52:54.5633333+00:00

Hi All,

One of my users is facing an issue logging into the legacy Outlook. The new Outlook for Mac works fine. However, when user reverts to the legacy Outlook, he encounters the following error. In the Azure AD sign in logs, I see the error below. Please guide me.

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Office: A suite of Microsoft productivity software that supports common business tasks, including word processing, email, presentations, and data management and analysis.Mac: A family of Apple personal computers that run the macOS operating system.
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Outlook: A family of Microsoft email and calendar products.Management: The act or process of organizing, handling, directing or controlling something.
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Accepted answer
  1. Alex Zhang-MSFT 6,390 Reputation points Microsoft External Staff
    2025-02-14T02:56:21.69+00:00

    Hello, @Roger Roger,Welcome to the Microsoft Q&A platform!

    Did he encounter the same issue on Outlook for Windows? Please kindly understand that the Outlook tag here we mainly focus on general issues about Outlook desktop client.

    From my personal perspective, I would suggest you try the following methods:

    1. Verify Credentials: Ensure that the user's credentials are correct and that there are no typos.
    2. Modern Authentication: Legacy Outlook versions might have issues with modern authentication. Ensure that modern authentication is enabled for the user's account. You can check this in the Microsoft 365 admin center.
    3. Clear Cached Credentials: Sometimes, cached credentials can cause issues. Clear the cached credentials from the Credential Manager on the user's machine:
      • Open Control Panel.
      • Go to Credential Manager.
      • Remove any credentials related to Outlook or Office.
    4. Update Outlook: Ensure that the legacy Outlook client is updated to the latest version. Sometimes, updates include fixes for authentication issues.
    5. Re-add Account: Remove the account from Outlook and then add it again. This can help reset any misconfigurations.

    If these steps don't resolve the issue, Microsoft has a dedicated support team for Outlook for Mac. It is suggested that you directly contact this support team by clicking Contact Support in the Help menu in Outlook for Mac. That team will assist you further. We sincerely appreciate your support for our products and services.  

    If the answer is helpful, please click on “Accept answer” as it could help other members of the Microsoft Q&A community who have similar questions and are looking for solutions.

    Thank you for your support and understanding.

    Best Wishes,

    Alex Zhang

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