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.
Next.js Image Component Fails to Optimize Images
Diagnose and fix root causes when Next.js <Image> skips optimization. Covers config, domains, loader issues, and CDN missteps beyond the basics.
React List Rendering: Diagnosing and Fixing Key Prop Warnings
How to debug and resolve React's list key prop warnings, including subtle runtime issues beyond console noise. Concrete steps, root causes, and real-world incident.
Next.js Static Site Generation Build Failures: Diagnosing getStaticProps and getStaticPaths Issues
Concrete diagnosis and fixes for Next.js static generation (SSG) build failures, covering getStaticProps, getStaticPaths, missing data, and non-obvious traps.
Diagnosing `ref.current` Is Null in React
A practical guide to tracing and fixing cases where a React ref's `current` is unexpectedly null, including async pitfalls and strict mode quirks.
Diagnosing and Resolving Next.js Server Action Errors
Pinpoint and fix errors in Next.js server actions, focusing on non-obvious causes like serialization and environment mismatches.
Diagnosing React Router Infinite Redirect Loops
How to fix and prevent infinite redirect loops in React Router—pinpoint the logic errors, misconfigurations, and unexpected auth flows that cause them.
Long-form thinking on debugging habits, observability, and the systems around the bug.
Tracking Down a 200 MB Leak with Python Memory Profilers
A production API was silently leaking 200 MB of RAM every hour. Here's how memory profilers found the culprit—a forgotten NumPy array reference—and how you can apply the same techniques.
Reading CPU Flame Graphs: What the Hot Colors Actually Tell You
Flame graphs are everywhere, but most engineers read them wrong. Here's how to identify real bottlenecks, avoid common misinterpretations, and turn profile data into actionable fixes.
When Logs Lie: The Gaps Between What You Log and What Actually Happened
Logs are the first thing we reach for during an incident. But they can be misleading, incomplete, or outright wrong. Here's when to trust them and when not to.
Adding Observability to a 500K-Line Monolith Without a Rewrite
Adding structured logging, distributed tracing, and metrics to a legacy monolith without a full rewrite. Real code examples and a war story from a 500K-line codebase.
Distributed Tracing: Following a Single Request Across Microservices
Distributed tracing lets you follow a request as it hops across services. I'll show you how trace context propagates, why sampling matters, and how tracing helped us debug a 5-second latency spike in production.
Structured Logging in JSON: Fields, Schemas, and Pitfalls from Production
A practical guide to designing JSON log schemas that are queryable, consistent, and actually useful in production — with field recommendations and a war story.