Issue Summary

When a non-image file (e.g., .txt, .pdf, .csv) is referenced inline using wiki markup notation 

(!filename.txt!, !filename.txt|thumbnail!, or !filename.txt|inline!)

 the rendered API output (expand=renderedFields / expand=renderedBody) displays an error instead of a graceful fallback. This same error is also exposed to end customers in JSM Customer Notification emails:

<span class="error">Unable to embed resource: basic-text.txt of type text/plain</span>

This same error is also exposed to end customers in JSM Customer Notification emails. 

https://jira.atlassian.com/browse/JSDCLOUD-11572 was closed as Fixed, however the issue persists in the rendered API output and JSM notification emails.

Steps to Reproduce

• Create an issue via REST API v2 (POST /rest/api/2/issue) with the description containing a non-image file reference, e.g.:

 "description": "Testing inline file reference:\n\n!basic-text.txt|thumbnail!"

curl -X POST \   -u email:token \   -H "Content-Type: application/json" \   "https://somehost.atlassian.net/rest/api/2/issue" \   -d '{     "fields": {       "project": { "key": "ITSM1" },       "summary": "Test - Non-image attachment rendering",       "issuetype": { "name": "Task" },       "description": "Testing inline file reference:\n\n!basic-text.txt|thumbnail!"     }   }' 

• Attach file basic-text.txt to the issue via Add Attachment API

  POST /rest/api/3/issue/{issueKey}/attachments
  
  curl -X POST \
    -u email:token \
    -H "X-Atlassian-Token: no-check" \
    -F "file=@/path/to/basic-text.txt" \
    "https://somehost.atlassian.net/rest/api/3/issue/ITSM1-10/attachments"
  

• Call: 

  GET /rest/api/3/issue/{issueKey}?expand=renderedFields

• Observe the renderedFields.description field
• (Optional) If the issue is in a JSM project with a Request Type and customer Reporter, check the JSM Customer Notification email

Expected Results

Non-image file references should gracefully degrade to a clickable link or filename, not display a raw error message, especially in customer-facing notifications.

Actual Results

The rendered description shows:

<p><span class="error">Unable to embed resource: basic-text.txt of type text/plain</span></p>

The same error is visible to end customers in JSM notification emails.

Workaround

Currently there is no known workaround for this behavior. A workaround will be added here when available