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.
Stripe Webhook Signature Verification Failed: A Debugging Guide
Diagnose and fix Stripe webhook signature verification failures. Covers common causes like clock drift, wrong signing secret, and raw body mismatches.
OpenAI API 429 Rate Limit Error: Diagnosis and Fixes
A focused guide on diagnosing and resolving HTTP 429 rate limit errors from the OpenAI API, covering root causes, retry strategies, and monitoring.
SendGrid Email Not Delivered: Diagnosing Silent Delivery Failures
A practical guide to diagnosing why SendGrid emails are accepted but never arrive, covering SPF/DKIM, bounces, suppression lists, and IP reputation.
Debugging LangChain Chain Output Errors: A Practical Guide
A hands-on guide to debugging LangChain chain output errors, covering common causes, quick diagnosis, and fixes.
Firebase Security Rules Blocking Requests: Debugging Guide
A practical guide to debugging Firebase Security Rules that unexpectedly deny requests. Covers simulator pitfalls, missing auth tokens, and rule ordering issues.
Debugging Firebase Realtime Database Offline Sync Failures
A focused guide to diagnosing and fixing when Firebase Realtime Database fails to sync data while offline, covering local state mismatches, conflict resolution, and connectivity edge cases.
Long-form thinking on debugging habits, observability, and the systems around the bug.
Mocking External APIs in Tests: Why stubbing HTTP is harder than it looks
Stubbing HTTP calls seems easy until a subtle mismatch between your mock and the real API causes a production incident. Here's what I learned the hard way.
How I Diagnosed a 1-in-1000 Race Condition in Our CI Pipeline
A race condition that only appeared once every thousand CI runs took weeks to track down. Here's how we finally caught it, what tools helped, and what we changed to prevent similar bugs.
How Database Indexes Work: A Debugging Story
A practical guide to understanding database indexes through the lens of debugging a real production outage caused by a missing covering index.
Reading PostgreSQL EXPLAIN ANALYZE Output: A Practical Guide with Real Query Examples
EXPLAIN ANALYZE is the single most important tool for diagnosing slow queries. Here's how to read the output, spot common pitfalls, and fix them with real-world examples.
When caches lie: debugging stale data in distributed systems
Cache invalidation is often cited as one of the two hard problems in CS, but the daily reality is subtler: partial staleness, clock drift, and silent evictions. This post walks through real debugging techniques for stale data in Redis, Memcached, and CDN layers.
Debugging Cache Invalidation Failures: A Case Study with Redis and PostgreSQL
Cache invalidation sounds simple — write-through, TTLs, done. But in practice, silent failures hide in race conditions, connection pools, and stale read replicas. Here's a real debugging story with Redis and PostgreSQL that taught me how to find them.