Cannot find the '@angular/common/http' module

Important Update:

HttpModule and Http from @angular/http has been deprecated since Angular V5, should of using HttpClientModule and HttpClient from @angular/common/http instead, refer CHANGELOG.

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For Angular version previous from **@4.3.0, You should inject Http from @angular/http, and HttpModule is for importing at your NgModule's import array.

import {HttpModule} from '@angular/http';

@NgModule({
  ...
  imports: [HttpModule]
})

Inject http at component or service

import { Http } from '@angular/http';

constructor(private http: Http) {}

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For Angular version after(include) 4.3.0, you can use HttpClient from @angular/common/http instead of Http from @angular/http. Don't forget to import HttpClientModule at your NgModule's import array first.

Refer @echonax's answer.

Important: HttpClientModule is for Angular 4.3.0 and above. Check @Maximus' comments and @Pengyy's answer for more info.

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Original answer:

You need to inject HttpClient in your component/service not the module. If you import HttpClientModule in your @NgModule

// app.module.ts:
 
import {NgModule} from '@angular/core';
import {BrowserModule} from '@angular/platform-browser';
 
// Import HttpClientModule from @angular/common/http
import {HttpClientModule} from '@angular/common/http';
 
@NgModule({
  imports: [
    BrowserModule,
    // Include it under 'imports' in your application module
    // after BrowserModule.
    HttpClientModule,
  ],
})
export class MyAppModule {}

So change

constructor(private httpClient: HttpModule) {}

to

constructor(private httpClient: HttpClient) {}

as it's been written in the documentation

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However, since you imported the HttpModule

you need to inject constructor(private httpClient: Http) as @Maximus stated in the comments and @Pengyy in this answer.

And for more info on differences between HttpModule and HttpClientModule, check this answer