Hi,
I think it has to do with Ionic 3.
See this thread
The point is that you have to be sure that your file ‘app.module.ts’ imports Angular’s HttpModule.
So import HttpModule in the ‘app.module.ts’ like this
import { HttpModule } from '@angular/http';
Then update your ‘imports’ (in app.module.ts) like this to consider providers related to ‘@angular/http’
imports: [
BrowserModule,
HttpModule,
IonicModule.forRoot(MyApp)
],