In the new Outlook, selecting Download All returns a 400 error.

Wesley_朱文俊 0 Reputation points
2026-09-10T02:59:03.9233333+00:00

When using the new Outlook, I can save the attachments in a single email individually, but if I click Download All directly, it returns a 400 error, and then Outlook freezes and has to be force-quit.

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Microsoft 365 and Office | Other
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  1. TaoLi 110.6K Reputation points Independent Advisor
    2026-09-10T03:46:18.2966667+00:00

    Hello,

    Since individual attachments download correctly but Download all returns a 400 error and freezes new Outlook, I suggest repairing the new Outlook app first.

    Go to Settings > Apps > Installed apps > Outlook (new) > Advanced options > Repair.

    If it still happens, return to the same page and select Reset, then sign in again.

    Microsoft instructions:

    https://support.microsoft.com/en-us/windows/apps/repair-apps-and-programs-in-windows

    If the issue remains, please test Download all for the same email in Outlook on the web:

    https://outlook.office.com/mail/

    If it works on the web, the issue is most likely with the local new Outlook app, and reinstalling new Outlook would be the next step:

    https://support.microsoft.com/en-us/outlook/getstarted/outlook-for-windows-not-responding-hangs-freezes-or-stops-working

    Regards,

    TaoLi

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