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.
Deployment config mismatch: how to debug environment-specific config bugs
Your staging environment works. Production does not. The code is the same but the config is different — a missing setting, a wrong endpoint, or a different feature flag value.
Feature flag bug: how to debug unexpected feature flag behaviour
A feature flag is supposed to be off for some users but is on for everyone, or vice versa. The flag value, targeting rules, or flag evaluation is wrong.
Session cookie not working after deployment: how to debug it
Users were logged in. You deploy. Everyone is logged out. The session cookie is not being sent, not being recognised, or being set with wrong attributes after the new deployment.
Redirect URL wrong in production: how to debug redirect bugs
Your app redirects users to `http://localhost:3000/dashboard` in production. The redirect URL is hardcoded, or the origin detection is picking up the wrong value.
OAuth callback URL mismatch: how to debug OAuth redirect errors
OAuth login fails with 'redirect_uri_mismatch' after deployment. The callback URL in the request does not exactly match what is registered with the OAuth provider.
Database migration works locally but fails in production: how to debug it
Your migration runs perfectly on your local database but errors out in production. Different database version, different data, or different permissions.
Long-form thinking on debugging habits, observability, and the systems around the bug.
Sentry Error Monitoring: A Practical Setup Guide from a Production Outage
A step-by-step setup guide for Sentry error monitoring, covering source maps, release tracking, grouping rules, and alerting — with a real story of a production outage that taught us the hard way.
Reading Prometheus Alert Rules: A Practical Reference for Debugging Firing Alerts
Alert rules look straightforward until you're staring at a firing alert at 3 AM. This post covers the structure, common traps, and how to extract actionable intent from any rule.
Debugging Network Issues with Chrome DevTools: Timing, Waterfalls, and Hidden Columns
A practical guide to diagnosing slow requests, stalled connections, and caching bugs using the Network tab's non-obvious features.
Finding Jank in React Apps with Chrome DevTools Performance Tab
A practical walkthrough of the Performance tab for diagnosing frame drops and long tasks in React apps, with a real debugging story.
Using Breakpoints Effectively: Beyond Step and Continue
Most engineers know F9 to set a breakpoint and F5 to run. But breakpoints have hidden superpowers — conditional, logpoint, hit-count, and data breakpoints — that can cut debugging time in half. Here's how to use them with real examples.
Conditional Breakpoints: When and How to Use Them Beyond the Basics
Conditional breakpoints stop only when a specific condition is true, reducing noise in loops and high-frequency code. Here's how to wield them in Chrome DevTools, VS Code, and IntelliJ, plus a war story about a subtle race condition.