getAttachmentContentAsync fails with error code 5001 when file is attached via Windows "Send to" context menu

[Hfcda]

Your Environment
Platform: PC desktop

Host: Outlook

Office version number: 2602 build 19725.20152

Operating System: Windows 11

Browser: N/A

Expected behavior
getAttachmentContentAsync should successfully retrieve attachment content (Base64) for all file types (csv, txt, pdf, jpg, etc.) when a file is attached via the Windows 11 right-click "Send to > Mail recipient" context menu.

Current behavior
getAttachmentContentAsync returns Failed with the following error for csv, txt, and pdf files:

{
"status": "failed",
"code": 5001,
"message": "An internal error has occurred."
}

jpg files are unaffected and return successfully.
Re-attaching the file manually resolves the issue.

Steps to reproduce
Right-click a file (csv, txt, or pdf) in Windows 11 Explorer

Select "Send to" > "Mail recipient"

Outlook opens a new compose window with the file already attached

Send the email

The ItemSend add-in event fires and calls getAttachmentContentAsync for the attachment

The callback receives result.status === "failed" with error code 5001

Link to live example(s)
N/A

Provide additional details
The issue is reproducible only when the attachment is added via the Windows "Send to" context menu

Manually re-attaching the same file (drag & drop or Attach File button) resolves the issue

jpg files attached via the same "Send to" method do NOT reproduce the issue

Affected file types confirmed: csv, txt, pdf

Context
This issue occurs in an ItemSend add-in that uses getAttachmentContentAsync to retrieve attachment content for processing before send. When users attach files via the Windows "Send to" shortcut (a common workflow), the add-in fails to retrieve the attachment content and blocks sending.

Useful logs
Console errors
{
"status": "failed",
"code": 5001,
"message": "An internal error has occurred."
}

[github-actions]

Here are some similar issues that might help you. Please check if they can solve your problem.

• Internal Server Error when Fetching Attachment Content with getAttachmentContentAsync on Mac :- 9HENJ7JB #6333
• Outlook on Mac - New UI - getAttachmentContentAsync() fails inside ItemSend handler with Error 5001 'Internal error has occurred' #2658
• [Outlook] Outlook desktop is unable to get attachment content, if email was created by Right click -> Send to -> Mail recipient #3547
• getAttachmentContentAsync() fails with internal server error 5001 #2842

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Possible solution (Extracted from existing issue, might be incorrect; please verify carefully)

Solution 1:

Upgrade Outlook to the latest version and check if the issue persists. This has resolved the issue for some users.

Reference:

• [Outlook] Outlook desktop is unable to get attachment content, if email was created by Right click -> Send to -> Mail recipient #3547 (comment)
• [Outlook] Outlook desktop is unable to get attachment content, if email was created by Right click -> Send to -> Mail recipient #3547 (comment)

Solution 2:

If the issue persists, collect diagnostic logs immediately after reproducing the issue and share them with the development team for further investigation. This can help identify the root cause of the problem.

Reference:

• getAttachmentContentAsync() fails with internal server error 5001 #2842 (comment)
• getAttachmentContentAsync() fails with internal server error 5001 #2842 (comment)

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[Hfcda]

Both of the above tickets appear to have been closed unresolved.

[Hfcda]

getAttachmentContentAsync( attachmentID, { asyncContext: { ... } }, (result) => { if (result.status === Office.AsyncResultStatus.Succeeded) { ... resolve(); } else { reject(); <- here } }

[ElizabethSamuel-MSFT]

@Hfcda Thanks for sharing this with us. Can you also note if you're using classic or new Outlook on Windows?

@exextoc Can you take a look?

Thanks.

[ndeleuze]

@Hfcda, do you see this API failing when called from the Taskpane or only during the ItemSend event?

[Hfcda]

@ElizabethSamuel-MSFT

The "Send to" feature via right-click on Windows launches Classic Outlook, not the new Outlook. So the feature only works in Classic Outlook.

@ndeleuze

I have only tried it with the ItemSend event so far, so I am not sure if it also fails when called from the Taskpane. I will try it when I get a chance.