This guide covers the top 10 Nginx and API gateway production faults—including 502/504 errors, retry storms, load imbalance, rate limiting failures, CORS issues, and 499 errors—with root cause analysis, configuration fixes, and a step-by-step SOP for rapid diagnosis and long-term prevention.
A CFO built a SaaS product in two days using Claude Code, but a missing database field caused the task queue’s automatic retries to re‑execute 21 LLM calls, turning a single day’s AI usage into a cost that exceeded the entire month’s server expenses.
A CFO used Claude Code to launch a SaaS product in two days, but a hidden bug caused the system to repeatedly retry successful LLM calls, turning a single day's AI usage into a month's worth of server expenses, prompting a detailed post‑mortem on cloud cost and retry‑storm pitfalls.
A senior cloud engineer discovers that a batch job built by a non‑technical CFO using Claude Code repeatedly retried a failed database write, causing a single day's worth of LLM API calls to incur the same cost as an entire month of server operation.
A CFO used Claude Code to launch a SaaS product in two days, but a missing database field combined with an automatic retry mechanism caused a single day's AI API calls to generate costs equivalent to a whole month's server expenses, prompting a detailed post‑mortem on the root causes and preventive measures.
