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.
Zustand Persist Middleware Not Saving or Loading State
How to diagnose and fix persistent state bugs with Zustand's persist middleware in React. Get concrete steps, real root causes, and effective solutions.
React Query Not Refreshing Stale Data Despite Invalidations
Diagnose and resolve cases where React Query fails to update stale data, even when invalidations or refetches are expected to trigger.
“Module Not Supported” Errors in Next.js Edge Runtime
A real-world guide to diagnosing and fixing 'module not supported' errors when deploying Next.js projects to the Edge Runtime.
React Portal Allows Click Events to Bubble Outside Intended DOM
When using React portals, click or key events can bubble up to unexpected ancestors, triggering handlers outside their intended boundaries.
Diagnosing tRPC Procedure Errors in Next.js Apps
Pinpoint and resolve tRPC procedure errors in Next.js projects. Covers error signatures, hidden pitfalls, common root causes, and real-world troubleshooting steps.
Vue Reactive Property Not Updating in Template
Diagnose and resolve cases where Vue's reactive data fails to reflect changes in the UI, including edge cases beyond the classic pitfalls.
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.