Square Payment Processing Bug Fix

My website relies on Square’s payment API, but every time a customer tries to pay, the transaction fails mid-processing and nothing useful shows up on-screen—no error code, no log entry, just an abandoned checkout. I can reproduce the issue consistently in both live and sandbox modes, so the problem is buried somewhere in the current integration rather than on Square’s side.

I need the integration audited, the root cause isolated, and a clean fix implemented so payments run through without a hitch. Once the code is patched, I also want clear guidance on what was changed and how to monitor future issues through Square’s dashboard and webhooks.

Deliverables
• Diagnosis summary pinpointing the failure point in the payment flow
• Updated code (JavaScript/PHP or relevant language) that processes payments successfully
• End-to-end test proving a completed transaction in both sandbox and live environments
• Brief hand-off notes so I can maintain the integration confidently

If you have solid Square API experience, can read network traffic, and know your way around webhooks and error logging, you’ll be able to turn this around quickly.