12 Most Common DevOps Errors That Trigger On-Call Alerts and How to Diagnose Them

A DevOps practitioner has catalogued the twelve production errors most likely to trigger on-call pages, noting that a small set of failure modes accounts for the vast majority of incidents. Common culprits include Kubernetes issues like CrashLoopBackOff, ImagePullBackOff, and OOMKilled, each of which has a distinct first diagnostic step that differs from the obvious guess. Other frequent offenders are Postgres connection exhaustion, DNS resolution timeouts inside pods, and 502 Bad Gateway errors, all of which tend to mislead engineers toward the wrong fix. For each error, the guide emphasizes checking a specific command or log source first — such as kubectl logs --previous or dmesg — before making any configuration changes. The core finding is that production outages are rarely caused by exotic bugs, but rather by the same recurring failure patterns appearing in slightly different contexts.