Angular Lazy Loading Error Fix

In this tutorial, you'll learn about Angular Lazy Loading Error Fix. We cover key concepts, practical examples, and best practices to help you understand and apply this topic effectively.

The Problem

Error: Cannot find module 'app/feature/feature.module'
or its corresponding type declarations.

Angular cannot resolve the lazy-loaded module path.

Wrong

const routes: Routes = [
  {
    path: 'feature',
    loadChildren: './feature/feature.module#FeatureModule', // Angular 8- syntax
  },
]

Output: build error or runtime error — the old string syntax is not supported in Angular 9+.

Right

const routes: Routes = [
  {
    path: 'feature',
    loadChildren: () => import('./feature/feature.module').then(m => m.FeatureModule),
  },
]

Ensure the feature module has its own routing:

// feature.module.ts
@NgModule({
  imports: [RouterModule.forChild([
    { path: '', component: FeatureComponent },
  ])],
})
export class FeatureModule {}

Expected output: the feature module is loaded lazily when navigating to /feature.

Prevention

• Use dynamic import() syntax for Lazy Loading (Angular 9+)
• Add RouterModule.forChild() in the lazy-loaded module
• Verify module path is relative to the route configuration file

Common Mistakes with Lazy Loading

1. Placing the wildcard pattern first in case expressions, making all subsequent patterns unreachable
2. Using head and tail instead of pattern matching, causing runtime errors on empty lists
3. Forgetting that lazy evaluation defers computation until the value is forced, causing space leaks with unevaluated thunks

These mistakes appear frequently in real-world ANGULAR code. DodaTech's contributors have identified these patterns through analysis of open-source projects and production systems.

Practice Exercise

Write a pure function that safely divides two integers using Maybe, then test it with edge cases like division by zero and negative numbers.

This exercise reinforces the concepts covered in this guide. Try implementing it before checking online solutions.

FAQ