Could not find a generator for route RouteSettings

Why This Happens

In Flutter, when you push a named route that is not defined in MaterialApp's routes map or onGenerateRoute, the navigator cannot create the route. Ensure all route names are registered or implement an onUnknownRoute handler.

The Problem

Navigator.pushNamed(context, '/details'); // Not in routes!

MaterialApp(
  routes: {
    '/': (context) => HomePage(),
    // '/details' is missing!
  },
)

The Fix

Navigator.pushNamed(context, '/details');

MaterialApp(
  routes: {
    '/': (context) => HomePage(),
    '/details': (context) => DetailsPage(),
  },
  onUnknownRoute: (settings) => MaterialPageRoute(
    builder: (_) => NotFoundPage(),
  ),
)

Step-by-Step Fix

1. 1

   Identify the error

   Look at the error about missing route generator. The pushed route name is not registered in the app.

2. 2

   Find the cause

   Check the routes map in MaterialApp and verify the route name matches exactly, including the leading slash.

3. 3

   Apply the fix

   Add the missing route to the routes map, or implement onGenerateRoute/onUnknownRoute for dynamic routing.