I need a sharp Magento 2 troubleshooter to jump on AnyDesk and resolve an urgent cart / checkout failure. At the moment, pressing “Add to Cart” throws an error message and the item never lands in the cart, so customers can’t proceed to the checkout at all. Here’s what I expect from you during the live session: • Pin-point the root cause behind the Add-to-Cart and subsequent checkout blockage (whether that lies in JavaScript conflicts, cache/session handling, quote tables, or a module override). • Apply a clean fix directly on the running instance—no staging copy available—while keeping code changes minimal and well commented. • Validate the result with me in real time: product must add successfully, cart totals update, and the full checkout flow (shipping, payment, order placement) completes without errors. You’ll have full AnyDesk access with terminal and Magento admin ready; feel free to lean on CLI tools (bin/magento, composer), browser console, or log files as needed. Once we confirm the flow is solid, I’ll clear caches and redeploy static content myself. If you’re confident troubleshooting live on production and can wrap this up quickly, let’s get started.