Upgrade JoomGallery, Preserve Custom Modifications

My Joomla 5 site runs JoomGallery 4.01 with more than 150,000 images and extensive core-level tweaks. I need the component brought up to version 4.20 while keeping every existing custom function intact.

The job starts with a full code-base diff: you will identify what I added or changed in my copy of JoomGallery compared with the official 4.01 release. Once those differences are mapped, you will merge them cleanly into 4.20, resolving any conflicts that appear during the upgrade. Nothing in the front-end experience—special layouts, category logic, upload handling, or permission rules—can break or behave differently after the move.

Please plan for:

• Safe staging environment, database backup and restore
• Incremental upgrade steps so the gallery remains online or suffers only minimal downtime
• Post-upgrade testing on bulk image browsing, search, and metadata edits
• Clear documentation of all code carried forward or newly adapted

Hand-off is complete when the live site runs JoomGallery 4.20 flawlessly with every custom feature verified.