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.
Queue consumer not processing messages: how to debug it
Messages pile up in the queue but your consumer does nothing. The consumer might be crashed, stuck, or silently discarding messages.
JWT token invalid after deployment: how to debug it
JWTs work locally and in staging, but after a production deploy every token is rejected. The secret, algorithm, or clock changed.
Node version mismatch in CI: how to debug it
Your code uses a feature from Node 20 but CI runs Node 18. Build fails with a syntax error or missing API. The fix is one line in the CI config.
npm install works locally but fails in CI: how to debug it
npm install completes on your machine but CI throws errors. The issue is usually a clean environment gap: missing native build tools, lockfile drift, or platform-specific binaries.
File upload works locally but fails in production: how to debug it
Your upload endpoint works with local files but returns errors in production. The filesystem, permissions, size limits, or storage backend is different.
API returns 500 only in production: how to debug it
Your API endpoint returns 200 locally but 500 in production. Some code path that never triggers in dev fires in the real environment.
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.