Blog · Error Fixes
Error Fixes
Step-by-step fixes for the errors developers hit most — the real causes and copy-paste solutions, tested in the browser.
How to Fix "Cannot Read Properties of Undefined" in JavaScript
The most common JavaScript error, explained: what triggers "Cannot read properties of undefined (reading 'x')", the six usual causes, and the exact fix for each — with copy-paste code.
Error FixesHow to Fix "Module Not Found" (Node, webpack, Vite & Next.js)
Cannot find module, Can't resolve, Failed to resolve import — the resolver could not map your import to a real file or package. Here are the six causes and the exact fix for each.
Error FixesHow to Fix "npm ERR!" — ERESOLVE, E404, EACCES and More
Every npm error starts with npm ERR! — the fix depends on the code. Here is what ERESOLVE, ELIFECYCLE, E404, ENOENT and EACCES mean, and how to resolve each.
Error FixesHow to Fix PHP "Parse error: syntax error, unexpected"
A PHP parse error stops the file before it runs — a missing semicolon, an unmatched brace, an unclosed string, or newer syntax on an older PHP. Here is how to find and fix each.
Error FixesHow to Fix Python "ModuleNotFoundError: No module named"
ModuleNotFoundError means Python searched every path and never found the module — usually the wrong interpreter or venv, or an install-name that differs from the import-name. Here is the fix.
Error FixesHow to Fix React Hook Errors (Invalid Hook Call & More)
Invalid hook call, missing dependency, "rendered more hooks than…", too many re-renders — the four React Hook errors developers hit most, with the real cause and fix for each.
Error FixesHow to Fix "ReferenceError: x is not defined" in JavaScript
Why "ReferenceError: x is not defined" happens — an identifier that was never declared in a reachable scope — and the six fixes, from typos and scope to the temporal dead zone.
Error FixesHow to Fix "TypeError" in JavaScript (Every Common Type)
A TypeError means you used a value the wrong way — calling a non-function, reassigning a const, iterating a non-iterable, or reading a property of null. Here is the fix for each.
Error FixesHow to Fix "Unexpected Token" in JavaScript & JSON
SyntaxError: Unexpected token usually means the input is not the syntax the parser expected — HTML fed to JSON.parse, uncompiled JSX, or an ESM/CommonJS mismatch. Here is the fix for each.
Error FixesHow to Fix Vue "Failed to Resolve Component"
[Vue warn]: Failed to resolve component means Vue found a component tag but nothing registered under that name. Here are the six causes — missing import, registration, casing — and the fix.