Buglyst Blog
Learn to debug under pressure.
Playbooks for fast pattern recognition, guides for the full investigation, and articles for the engineering judgment around the edges.
17 playbooks · 509 guides · 95 articles · 12 linked practice labs ·skip to practice
Fast pattern recognition for the production failures engineers see most often.
17 playbooks
Debugging Env Var Issues
A concise checklist for incidents where local works but CI, staging, or production changes behavior.
Debugging Cache Stampedes
How to recognize and contain request spikes when cached data expires.
Debugging CORS Origin Bugs
A practical way to inspect origin parsing, credentials, and header behavior.
Debugging Retry Bugs
Retry issues often hide the first failure and create duplicate work.
Debugging Timezone Bugs
Time bugs usually live at day boundaries, DST changes, and unit conversions.
Debugging Pagination Bugs
Pagination bugs hide in boundary math, cursor reuse, and new records arriving between pages.
Structured investigations for the failure modes engineers meet in real systems.
Cron job not running in production: how to debug scheduled tasks
Your cron job runs fine when triggered manually but never fires on its schedule in production. The scheduler, timezone, or environment is wrong.
Worker process memory leak: how to find and fix memory leaks in background jobs
Your background worker's memory usage grows steadily until it crashes. The leak is accumulating across jobs — each job leaves something behind.
Rate limit bug: how to debug unexpected rate limiting issues
Legitimate users are hitting rate limits. The limiter is too aggressive, counting wrong, or sharing state across instances when it should not.
Request body undefined in Express: how to debug missing request bodies
Your Express route handler receives `req.body` as `undefined` or an empty object. The body parser is missing, misconfigured, or not matching the content type.
ESM CommonJS import error: how to debug module system conflicts
Your import breaks with 'require is not defined' or 'Cannot use import outside a module'. The file is being treated as the wrong module system.
GitHub Actions missing secret: how to debug CI secret issues
Your GitHub Actions workflow references a secret that does not exist in the repository settings. The workflow fails with an empty value or an error.
Long-form thinking on debugging habits, observability, and the systems around the bug.
Debugging Webhook Delivery Failures: What the Logs Don't Tell You
HTTP 200 doesn't mean your webhook was processed. A practical guide to the network and middleware layers that silently drop webhooks.
Debugging HTTP Headers with curl: From Basic Flags to Packet-Level Inspection
A practical guide to inspecting HTTP request and response headers with curl, covering basic flags, debugging tricky issues, and understanding what your headers are really doing.
Debugging WebSocket Real-Time Features: Packet Loss, Reconnect Storms, and Silent Failures
WebSocket debugging goes beyond console.log. I cover packet capture with tcpdump, reconnect backoff strategies, and a war story about a silent failure that took down a production chat feature.
Rest API Design Mistakes That Inject Bugs Into Your System
Most API bugs aren't in the implementation—they're baked into the contract. Here are the design errors I've seen cause the most production incidents.
Blameless Postmortems: How We Fixed Root Causes Without Firing Anyone
A practical guide to running postmortems that focus on systemic failures, not individual mistakes. Includes a real incident breakdown from a production database outage.
Chaos Engineering at 3 AM: When Our Kubernetes Cluster Lost Its DNS
We ran a chaos experiment on our Kubernetes cluster and found a subtle DNS misconfiguration that would have caused a cascading failure. Here's how we did it and what we learned.