Issue Summary

In Jira Cloud, adding attachments to comments intermittently fails for multiple users across multiple projects.

The issue affects different file types (e.g. images such as PNG, video files such as MP4/MOV, PDFs, and pasted screenshots), all of which are within the configured attachment size limit. The same file may sometimes be added successfully and at other times fail with an error, without any change to the file or the issue.

From the user’s perspective, the UI displays one of the following messages when attempting to add an attachment in a comment:

• “We couldn’t save your attachment”
• “We couldn’t save your comment”

From the network trace, the updateComment GraphQL mutation fails with an ATTACHMENT_VALIDATION_ERROR and HTTP status code 400, even though the attachment appears valid (supported type, below the configured size limit).

Steps to Reproduce

Note: Because this is intermittent, these steps do not always reproduce the error on the first attempt. Multiple attempts with the same file may be required.

1. Open any Jira Cloud issue in a project where attachments and comments are enabled.
2. Click “Add a comment”.
3. Attach a file to the comment by uploading (e.g. PNG/MOV/PDF) or pasting a screenshot. For example:
   • Image (PNG)
   • Video file (MOV/MP4, ~20–30 MB)
   • PDF
4. Clipboard image via OS screenshot tool (e.g. Command+Shift+4 on macOS, then paste into the comment)
5. Attempt to save/post the comment.
6. Observe that intermittently the operation fails with:
   • “We couldn’t save your attachment” or
   • “We couldn’t save your comment”
     and the comment/attachment is not saved.
7. Repeat the same steps with the same file and same issue; in some cases the operation later succeeds, indicating the file and configuration are valid.

Expected Results

When a user adds an attachment in a comment (by uploading a file or pasting an image):

• The attachment is successfully uploaded and associated with the issue/comment.
• The comment is saved without error.
• No “We couldn’t save your attachment” or “We couldn’t save your comment” error messages are shown, as long as the file meets configured limits and supported types.

Actual Results

Intermittently, when adding an attachment as part of a comment:

• The UI displays “We couldn’t save your attachment” or “We couldn’t save your comment”.
• The comment is not saved and/or the attachment is not added.
• Retrying with the same file and same issue may sometimes succeed, indicating the file itself is valid and the error is not purely deterministic.

Technical details from HAR / network trace:

The failing request is a GraphQL mutation to useSaveCommentRelayUpdateCommentMutation (e.g. via /gateway/api/graphql/...), with a response similar to:

{
  "data": {
    "jira": {
      "updateComment": {
        "__typename": "JiraUpdateCommentPayload",
        "success": false,
        "errors": [
          {
            "message": "ATTACHMENT_VALIDATION_ERROR",
            "extensions": {
              "__typename": "GenericMutationErrorExtension",
              "statusCode": 400
            }
          }
        ],
        "comment": null
      }
    }
  }
} 

Workaround

No reliable workaround identified.

Notes:

Retrying the operation (same file, same comment) sometimes works, but the behavior is intermittent and cannot be relied upon.

The issue occurs across different networks and browsers, and with files that are:

• Well under the global attachment size limit, and
• Standard, supported file types.

Because the same attachment can both fail and succeed under the same conditions, there is currently no consistent workaround that can be recommended.