ERROR Error: StaticInjectorError(AppModule)[UserformService -> HttpClient]:

While trying to add a PrimeNG table I broke my build here: https://github.com/BillyCharter87/Tech-O-Dex-UI/tree/BrokeIt

I recall updating my package.json from TypeScript 2.3.4 to 2.4.0 and it broke due to (I think) the fact that I was using Headers and Http for my POST call. I tried setting it back to 2.3.4 to no avail. I have fixed what I could by adding in:

import { HttpClient, HttpHeaders } from "@angular/common/http";

but still running into the Error I have now for the HttpClient. I have tried importing HttpClient into the providers like so: providers: [HttpClient] for my app.module.ts.

The full error is as follows:

AppComponent.html:9 ERROR Error: StaticInjectorError(AppModule)[HttpClient -> HttpHandler]: 
StaticInjectorError(Platform: core)[HttpClient -> HttpHandler]: 
NullInjectorError: No provider for HttpHandler!

Make sure you have imported HttpClientModule instead of adding HttpClient direcly to the list of providers.

See https://angular.io/guide/http#setup for more info.

The HttpClientModule actually provides HttpClient for you. See https://angular.io/api/common/http/HttpClientModule:

Code sample:

import { HttpClientModule, /* other http imports */ } from "@angular/common/http";

@NgModule({
    // ...other declarations, providers, entryComponents, etc.
    imports: [
        HttpClientModule,
        // ...some other imports
    ],
})
export class AppModule { }

Import this in to app.module.ts

import {HttpClientModule} from '@angular/common/http';

and add this one in imports

HttpClientModule

In my case there was a need for:

@Injectable({
    providedIn: 'root'  // <- ADD THIS
})
export class FooService { ...

instead of just:

@Injectable()
export class FooService { ...

Simply i have import in appmodule.ts

import { HttpClientModule } from '@angular/common/http';
  imports: [
     BrowserModule,
     FormsModule,
     HttpClientModule  <<<this 
  ],

My problem resolved

import the HttpClientModule in your app.module.ts

import {HttpClientModule} from '@angular/common/http';

...
@NgModule({
...
  imports: [
    //other content,
    HttpClientModule
  ]
})

provide all custom services means written by you in component decorator section Example : providers: [serviceName]

note:if you are using service for exchanging data between components. declare providers: [serviceName] in module level

There are two possible reasons

1. If you are using HttpClient in your service you need to import HttpClientModule in your module file and mention it in the imports array.

   import { HttpClientModule } from '@angular/common/http';

2. If you are using normal Http in your services you need to import HttpModule in your module file and mention it in the imports array.

   import { HttpModule } from '@angular/http'

By default, this is not available in the angular then you need to install @angular/http

If you wish you can use both HttpClientModule and HttpModule in your project.

Add HttpClientModule in your app.module.ts and try, it will work so sure. for example

import { HttpModule } from '@angular/http

There are two reasons for this error

1. In the array of import if you imported HttpModule twice

2. If you haven't import:

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

If you want then run:

npm install @angular/http