Property not assignable to base TypeScript TS2416

Why This Happens

In TypeScript, a class property doesn't match the parent class or interface. This is one of the most common TypeScript errors developers encounter. Understanding the root cause helps you fix it quickly and prevent it from recurring.

The Problem

class Dog extends Animal {
  name: number = 5; // string in Animal!
}

The Fix

class Dog extends Animal {
  name: string = 'Rex';
}

Step-by-Step Fix

1. 1

   Identify the error

   Look at the error message: TS2416: Property in type is not assignable to same in base. This tells you exactly what went wrong.

2. 2

   Find the cause

   Check the stack trace to find which line of your TypeScript code triggered this error.

3. 3

   Apply the fix

   Use the corrected code pattern shown above. Test to confirm the error is resolved.