Debugging & Troubleshooting
Reading the error, finding the real cause, and fixing it calmly instead of guessing.
Watch it animated → Interactive, click-through walkthroughs for Debugging & Troubleshooting concepts.Basic
What an Error Message Is Actually Telling You An error message is not the computer scolding you - it's a precise report of what went wrong and where. This guide teaches you to read its anatomy, recognize the common families, and work through one calmly.
Reading a Stack Trace at 2am A stack trace is the call stack frozen at the instant of failure - this guide teaches you to read one calmly: what it actually is, how to find your code in the noise, and how to go from trace to fix.
Reading Logs Without Drowning What logs actually are, how to find the one line that matters in a flood of them, and how to write logs that help future-you instead of burying them.
Intermediate
How to Reproduce a Bug Reproduction is the skill that makes every fix possible: turn a vague report into a bug you can trigger on demand, shrink it to its essence, and tame the intermittent ones that won't show up when you're watching.
Using a Debugger (Breakpoints, Stepping & Watch) What a debugger actually is - a way to pause your program mid-run and inspect everything that's true at that instant - and how breakpoints, stepping, and watch expressions transfer across every IDE, language, and browser devtools.
Bisecting a Bug (git bisect & Binary-Search Thinking) When something worked before and is broken now, you don't search commit by commit - you halve the suspect range each test, so 1000 commits take about 10 checks; git bisect automates the hunt, and the same halving idea finds the bad config line, input row, or dependency.
Debugging in the Browser Browser DevTools without the overwhelm: the Console, breakpoints in the Sources panel, and the Network tab solve most frontend mysteries.
Advanced
When Prod Is Down: Staying Calm How to handle a production outage without panicking: assess the blast radius, stop the bleeding before you diagnose, run the incident with clear comms, and turn the wreckage into a blameless postmortem that prevents the next one.