Office.context.mailbox.item.removeAttachmentAsync() call fails when removing attachments from multiple drafts

[MehakFatima24]

Provide required information needed to triage your issue

Your Environment

• Platform [PC desktop, Mac, iOS, Office on the web]: Office on the web
• Host [Excel, Word, PowerPoint, etc.]: ______
• Office version number: ______
• Operating System: Mac
• Browser (if using Office on the web): Chrome

Expected behavior

The attachments should be removed successfully from each draft.

Current behavior

Currently the attachments fail randomly, and the following error shows up on Outlook: "The following attachments couldn't be deleted: <Attachment_Name>. Please try again later." when we check the errors with the api (https://outlook.office.com/owa/service.svc?action=DeleteAttachment&app=Mail&n=), the response status code is 200 however when we take a look at the response there is a mismatch in the change key "The send or update operation could not be performed because the change key passed in the request does not match the current change key for the item., Cannot save changes made to an item to store.SaveStatus: IrresolvableConflict\r\nPropertyConflicts:\r\n"

Steps to reproduce

1. Create multiple drafts
2. Add attachments in each draft 4+
3. Switch between drafts
4. Open a draft and remove all attachments
5. Open another draft and remove attachments till you run into the problem

Context

The attachments are automatically removed by our add-in when the user clicks send. However, with this error the send button remains greyed out and the user remains stuck. This is negatively impacting a significant user base for our add-in.

Useful logs

• Console errors
• Screenshots
• Test file (if only happens on a particular file)

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[github-actions]

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

• Webaddin - OWA - Unable to remove attachments sometimes #5309
• Remove attachments from previously drafted email fails #1746
• Attachments intermittently become locked on a message and cannot be deleted or previewed in new outlook #4610

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

Solution 1:

This issue is mostly happening because the mail item is being saved by two entities (removeAttachments and setCustomProperties), sometimes causing a conflict at the server side. Implement the logic of retries while removing the attachments. Run a loop for 3 retries, if successful exit the loop, else delay the next retry by 1 or 2 seconds. This should resolve the issue.

Reference:

• Attachments intermittently become locked on a message and cannot be deleted or previewed in new outlook #4610 (comment)
• Attachments intermittently become locked on a message and cannot be deleted or previewed in new outlook #4610 (comment)

Solution 2:

The issue may be related to notification messages not having a unique ID across different drafts. Ensure that each notification message has a unique ID to avoid conflicts.

Reference:

• Remove attachments from previously drafted email fails #1746 (comment)
• Remove attachments from previously drafted email fails #1746 (comment)

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[arpitsangwanmsft]

Hey @MehakFatima24 !
Can you please help with a couple of questions for better understanding the issue:

• Does your Add-in use onMessageSend event?
• When do you fetch the attachmentIds(assuming through getAttachmentssync()) used to call removeAttachmentAsync()?
• Does the Add-in have a retry logic to delete attachments? (Though I acknowledge that the 200 response might be misleading in that scenario), if yes, are you able to delete the attachment after retrying ?

It would be really helpful If you can provide us with a sample addin through which we can repro this scenario, if not possible can you please provide sample code of how your Add-in is setup and has been calling above mentioned APIs?

Thanks

[MehakFatima24]

Hi @arpitsangwanmsft

• The addin doesn't use onMessageSend event, it uses onItemSend
• Yes we use getAttachmentasync to fetch the attachments and removeAttachmentAsync to remove them
• The addin does not have a retry logic in place but since we can reproduce this issue when we try to retry manually to remove these attachments it does not work in many cases specially with images. Also as you mentioned the 200 response is misleading since the method does not fail and its hard to know when something went wrong.

Here's a snippet of the code that we use to remove the attachments once the message is sent.

[lnnrtngl]

@exextoc, @arpitsangwanmsft

This issue is a critical blocker for our users transitioning from Outlook classic to OWA. The inability to reliably remove attachments from drafts is causing significant disruption, as users are unable to send these emails

The problem persists even with manual retries, especially with image attachments, and the misleading 200 response complicates debugging..

Currently this is undermining user confidence in the new OWA interface and impacting productivity significantly for our users

We need a resolution or workaround. Any updates or tips on this would be greatly appreciated