PrestaShop 1.7 Upgrade Assistance

I’m currently running PrestaShop 1.7.1.1 and want to move to the most recent stable release that won’t break my store. There are custom core modifications in place, but I do have complete file and database backups ready.

What I need from you:
• Audit the existing installation, including any overridden core files, to determine the highest version we can safely reach.
• Map out the upgrade path (staging copy, incremental jumps, or direct upgrade) and explain the risks for each step.
• Execute the upgrade on a staging environment first, making sure every installed module remains operational—especially payment, shipping, and product-handling extensions.
• Reapply or refactor my custom core tweaks where necessary so nothing is lost.
• Once everything passes testing, migrate the updated codebase and database to production and validate frontend, backend, and checkout flow.
• Provide a concise post-upgrade report with a rollback plan and tips for future updates.

You’re free to use the official 1-Click Upgrade module, manual FTP/MySQL methods, or another proven workflow; the goal is a smooth transition with zero downtime to customers.

If you have recent experience upgrading PrestaShop 1.7.x stores that contain custom edits, let me know your approach and timeframe.