Error: Unexpected value 'undefined' imported by the module

Question

I\'m getting this error after migrating to NgModule, the error doesn\'t help too much, any advice please?

Error: Error: Unexpected value \'undefined\' import         


        

Answer 1

My problem was having an export twice in index.ts

Removing one of them solved the problem.

Answer 2

In case your index exports a module - That module should not import its components from the same index, it should import them directly from the components file.

I had this issue, and when I changed from importing the components in the module file using the index to importing them using the direct file, this resolved.

e.g changed:

import { NgModule } from '@angular/core';
import { MainNavComponent } from './index';
@NgModule({
  imports: [],
  exports: [MainNavComponent],
  declarations: [ MainNavComponent ],
  bootstrap:    [ MainNavComponent ]
})
export class MainNavModule {}

to:

import { NgModule } from '@angular/core';
import { MainNavComponent } from './MainNavComponent';
@NgModule({
  imports: [],
  exports: [MainNavComponent],
  declarations: [ MainNavComponent ],
  bootstrap:    [ MainNavComponent ]
})
export class MainNavModule {}

also remove the now unnecessary exports from you index, e.g:

export { MainNavModule } from './MainNavModule';
export { MainNavComponent } from './MainNavComponent';

to:

export { MainNavModule } from './MainNavModule';

Answer 3

For me, this error was caused by just unused import:

import { NgModule, Input } from '@angular/core';

Resulting error:

Input is declared, but it's value never read

Comment it out, and error doesn't occur:

import { NgModule/*, Input*/ } from '@angular/core';

Answer 4

Had the same exception when tried to compile an Angular 5 application.

Unexpected value 'undefined' imported by the module 'DemoAppModule'

In my case it turned out it was a circular dependency which I found by using a tool madge. Found the files containing circular dependency by running

npx madge --circular --extensions ts src/

Answer 5

I had the same issue, I added the component in the index.ts of a=of the folder and did a export. Still the undefined error was popping. But the IDE pop our any red squiggly lines

Then as suggested changed from

import { SearchComponent } from './';

to

import { SearchComponent } from './search/search.component';

Answer 6

Unused "private http: Http" argument in the constructor of app.component.ts had caused me the same error and it resolved upon removing the unused argument of the constructor