File Explorer
Millarum File Explorer provides Jira users with a desktop-like tree navigation for attachments across projects, epics, and issues. Occasionally, user permission restrictions or browser security policies can interrupt media previews or file downloads.
This guide walks you through diagnosing and fixing the 3 most common attachment display issues.
Issue 1: "Unable to load preview — HTTP 403 Forbidden"
This error occurs when the currently logged-in Jira user lacks permission to access the underlying issue's attachments according to project permission schemes.
- Navigate to Project Settings > Permissions in Jira.
- Verify that the user's role includes the Browse Projects and View Attachments permissions.
- If issue-level security schemes are active, confirm the user belongs to the designated Security Level group.
Issue 2: PDF or Image Thumbnail Displaying Blank Box
Modern web browsers restrict third-party cross-origin requests (CORS) when rendering embedded PDF or media objects.
Fixing CORS & Third-Party Cookie Settings
If using Chrome or Safari, ensure Third-party cookies or Cross-site tracking preventions are not blocking standard Atlassian media CDN domains (*.atlassian.net and *.media.atlassian.com).
Issue 3: Files Uploaded to Jira Sub-tasks Not Appearing in Main Directory
By default, Millarum File Explorer aggregates attachments based on issue hierarchy (Project > Epic > Story > Sub-task).
- Open the File Explorer panel inside your Jira issue view.
- Ensure the toggle switch "Include Sub-task Attachments" is turned ON in the filter bar.
- Click Sync File Tree to trigger an updated fetch from Jira APIs.