Unable to Open Email Attachments (New Outlook)

Carson Fair 0 Reputation points
2026-11-06T17:42:22.2633333+00:00

Reporting a new issue in New Outlook: Version 1.2026.1026.100

When an email is received with an attachment (PDF, Excel, etc.), double-clicking the attachment to open it fails with a "Failed to open — restart Outlook" message. The only workarounds available are to preview the file or download it separately.

Additional details:

  • Double-clicking the email itself can also trigger the same "Failed to open — restart Outlook" error.
  • Restarting New Outlook does not resolve the issue.
  • Switching to Classic Outlook allows the attachment to open normally.
  • Reverting back to New Outlook afterward sometimes works — the attachment opens, but only after an initial "premature fail" message.
  • Continuously switching between Classic and New Outlook to work around this isn't a sustainable solution.

Current workaround: Using Outlook on the Web or Classic Outlook until this is resolved.

Already attempted to fix by deleting all contents int he "Attachments" folder under %userprofile%\AppData\Local\Microsoft\Olk
and this did not fix it.

Questions for the group:

  1. Does anyone know which recent MS/KB update introduced this issue?
  2. Is there an ETA on a patch or fix from Microsoft?
Outlook | Windows | New Outlook for Windows | For business
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  1. Ryan-N 16,940 Reputation points Microsoft External Staff Moderator
    2026-11-06T18:12:29.6466667+00:00

    Hi Carson,

    Welcome to the Microsoft Q&A forum.

    Based on the information I found, on October 28, Microsoft acknowledged an issue where the Outlook desktop app was unable to open attachments, under incident ID EX1528992.

    User's image

    At this time, a fix for this issue has been deployed. To ensure that the fix is applied and takes effect, please try the following steps:

    1. Sign out of Outlook, then sign back in.
    2. Clear the cache for New Outlook, then reopen the application and check whether the issue persists.

    If you have already completed the steps above but the issue is still occurring, I recommend contacting Microsoft Technical Support for further investigation. The support team can verify the service status and check whether the fix for this issue has already been applied to your tenant.

    You can refer to the instructions in the following documentation to create a support ticket with Microsoft Technical Support:

     Get support - Microsoft 365 admin | Microsoft Learn

    I hope this information is helpful.

    If you have any questions or need further assistance, please feel free to share them in the comments on this post so I can continue to support you.

    I look forward to continuing the conversation.

    If the answer is helpful, please click "Yes" and kindly upvote it.

    Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread. 

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