type 'List<dynamic>' is not a subtype of type 'List<String>'

Why This Happens

In Dart, JSON decoding produces List<dynamic> and Map<String, dynamic>. Assigning these directly to typed collections fails because Dart's type system is strict. Use .cast<T>() or .map() to convert the dynamic list to the expected type.

The Problem

final json = jsonDecode(response.body);
final List<String> names = json['names']; // List<dynamic> != List<String>

The Fix

final json = jsonDecode(response.body);
final List<String> names = List<String>.from(json['names']);

Step-by-Step Fix

1. 1

   Identify the error

   Look at the error message: type 'List<dynamic>' is not a subtype of type 'List<String>'. This is a type mismatch from JSON parsing.

2. 2

   Find the cause

   Check where JSON data is decoded and assigned to typed collections without explicit casting.

3. 3

   Apply the fix

   Use List<T>.from() or .cast<T>() to explicitly convert the dynamic list to the expected type.