Why req.user Breaks in Express + TypeScript (Real Reason & Fix)

Description

You’re not alone - this is one of the most common Express + TypeScript errors. In this video, we fix the TypeScript error where req.user is not defined on the Request object, and more importantly, understand WHY it happens from first principles. What we will learn: - Why req.user works in JavaScript but breaks in TypeScript - How Express Request typing actually works - Why TypeScript doesn’t trust runtime-added properties - How to extend Express Request using declaration merging - The correct and safe way to fix req.user typing - Common mistakes that cause this error again #TypeScript #ExpressJS #backenddevelopment #reqUser #ExpressTypeScript #NodeJS #JWTAuth #TypeScriptErrors #AuthMiddleware #StartedCoding