PHP applications often behave perfectly in local development but break mysteriously in production. This article reviews ten common hidden failure patterns that cause slowdowns, 502/504 errors, data corruption, duplicate background jobs, and even cascading outages. Key culprits include session file locking under concurrency, misconfigured opcache that serves stale code, database connection pool exhaustion, and improper handling of long-running requests. The author emphasizes that these issues rarely produce clear error logs, making them hard to trace without systematic monitoring and load testing. For engineering teams, this serves as a valuable postmortem checklist: check session storage, review opcache settings, monitor connection pools, and validate idempotency of background tasks. While the examples are PHP-specific, the underlying principles apply to any server-side language. The article is a good starting point for building more resilient production systems.
A practical roundup of subtle PHP production issues—session locking, opcache misconfig, DB connection exhaustion—that lead to 502s, slowdowns, and data races. Essential checklist for incident reviews.