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.
HTTP Connection Timeout: Debugging Network Stalls and Misconfigured Timeouts
A practical guide to diagnosing HTTP connection timeouts caused by network latency, firewall drops, TCP backlog exhaustion, and misconfigured timeout stack.
OAuth2 PKCE Code Challenge Verification Failed
This guide covers diagnosing and fixing PKCE code challenge verification failures in OAuth2 flows, including S256 hash mismatches and incorrect code verifier handling.
Debugging OAuth2 Authorization Code Flow Errors
A tactical guide to diagnosing failures in the OAuth2 authorization code flow, covering redirect URI mismatches, state validation, token endpoint issues, and common provider-specific pitfalls.
Debugging HTTP 429 Too Many Requests – API Rate Limit Guide
A hands-on guide to diagnosing, mitigating, and preventing HTTP 429 rate limit errors with specific tools and patterns.
WebSocket Connection Closing Unexpectedly: A Field Guide
A systematic approach to diagnosing why WebSocket connections drop, covering proxy timeouts, idle timeouts, load balancer quirks, and client-side keepalive failures.
Debugging gRPC Status Code Errors: Root Causes and Fixes
A practical guide to debugging gRPC status code errors, covering non-obvious causes like proxy interference, deadline propagation, and client/server version mismatches.
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.