Debugging & Errors
Why Is My HTML Not Showing Correctly?
Your page is blank, half-rendered, or nothing like the file you wrote. An ordered checklist from most to least likely cause, with…
Debugging & Errors
Your code broke and you do not know why. These guides explain what error messages mean, how to read a stack trace, and what to check first.
10 guides
Debugging & Errors
VS Code Problems Beginners Hit (and How to Fix Them)
Python not found, the wrong interpreter, imports that fail, a terminal in the wrong folder, Live Server not working. The setup problems…
Debugging & Errors
Why Is My Python Code Not Working?
A triage guide for when your Python program will not run or gives the wrong answer. The eight causes behind most beginner…
Debugging & Errors
How to Debug JavaScript in the Browser
Console logging that actually helps, breakpoints, stepping through code, and the Network tab — the four tools that solve nearly every front-end…
Debugging & Errors
Why Is My CSS Not Working? A Checklist
Your styles are not applying. Work through this ordered checklist — file linking, selector accuracy, specificity, inheritance and cascade order — to…
Debugging & Errors
How to Read a Stack Trace
A stack trace is a list of the function calls that led to an error. Here is how to read one in…
Debugging & Errors
Common JavaScript Errors and What They Mean
The JavaScript console errors beginners see most, what actually causes each one, and how to fix them — including the undefined error…
Debugging & Errors
Common Python Errors and How to Fix Them
The Python errors beginners hit most: SyntaxError, IndentationError, NameError, TypeError, ValueError, IndexError, KeyError and ModuleNotFoundError — each with a cause and a…
Debugging & Errors
How to Read Programming Errors (and Actually Fix Them)
Error messages are instructions, not insults. A repeatable method for reading any error, finding the real cause, and fixing it without guessing.
Debugging & Errors
Reading errors and stack traces (for beginners)
Error messages are instructions, not insults. Read the bottom line first, then the line above it, and most errors stop being frightening.
Related topics
Where to go next
Programming Basics
The ideas every language shares — variables, loops, functions and how a program actually runs.
10 guides
Python
Plain-English Python guides, from your first line of code to small programs that do real work.
14 guides
JavaScript
How JavaScript works in the browser, explained with short examples you can paste and run.
11 guides
Keep going — pick your next guide
The fastest way to improve is to read one guide, then build the thing it describes. Start with the basics, or jump straight to a project.