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.
How to Read Error Messages: A Debugging Protocol
Most engineers skim error messages and miss the signal. Here's a repeatable protocol for extracting maximum information from stack traces, log lines, and crash dumps — with a real incident walkthrough.
When to Escalate a Bug: A Decision Framework for Junior and Mid-Level Engineers
A practical framework for junior and mid-level engineers to decide when to escalate a bug, with real-world examples and criteria beyond time spent.
Debugging vs. Firefighting: Why Treating Production Incidents as Debugging Sessions Fails
When production goes down, your brain wants to debug. That instinct costs you hours. Here's why firefighting requires a fundamentally different approach, and the specific process I use to switch modes.
Writing an Incident Runbook That Actually Gets Used in Production
A runbook isn't a document—it's a tool. Here's how to write one that reduces MTTR and doesn't embarrass you during the next PagerDuty alert.
Debugging a production incident with your boss on Slack: staying rational when everything is on fire
A personal account of debugging a cascading Redis failure while the VP of Engineering watched, and the mental models that kept the fix from turning into a rollback.
Reading Distributed Traces to Find Latency: A Field Guide
Tracing tools generate a firehose of data. Here's how to filter the signal from the noise and actually find the root cause of high latency.