Worked on the mosaicml/composer repository to enhance backend reliability by improving error handling for private link access. Focused on Python-based solutions, the developer addressed a key bug where access-denied scenarios previously returned unclear errors. By raising PermissionError for HTTP 401 and 403 responses, unwrapping internal exceptions, and inspecting error details for permission-related messages, the changes now provide users with clearer, more actionable feedback. This targeted update streamlines troubleshooting and reduces support overhead for private data workflows. The work demonstrates strong backend development and error handling skills, resulting in more transparent and maintainable error reporting for secure object access.