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.
The Debugging Mindset: A Systematic Method for Finding Root Causes
A repeatable, hypothesis-driven approach to debugging that works for intermittent failures, performance regressions, and production incidents.
Analyzing a Core Dump: What to Do When Your Process Goes Silent
A core dump is your process's last scream. Here's how to make it talk.
Timeouts Every Engineer Gets Wrong (and How to Fix Them)
Most timeout bugs aren't logic errors — they're configuration failures. Here's how to stop treating timeouts as magic numbers and start engineering them deliberately.
Backpressure in Streaming Systems: When Your Pipeline Fights Back
Backpressure is the system's way of saying 'slow down.' Ignore it and you get OOM crashes, silent data loss, or cascading failures. Here's how to design for it.
Finding Memory Leaks Step by Step: A Systematic Approach
Memory leaks are the silent killers of long-running services. Here's a repeatable process to hunt them down, from heap dumps to production monitoring.