In app.module.ts I add ReactiveFormsModule in my imports section. Remember to import it at the top as: import { ReactiveFormsModule} from '@angular/forms.

In your app.component.ts you have to define FormGroup instance and initialize/register it via ngOnInit method as below:

    import { FormGroup, FormControl } from '@angular/forms'; //imports
.......................................................................
    myForm:FormGroup;  
    ngOnInit(){
         this.myForm = new FormGroup({          
               'name':new FormControl(null), //note, can have up to 3 Constructor Params: default value, validators, AsyncValidators
               'email':new FormControl(null,Validators.email)

          })
    }

Then bind form to the FormGroup instance myForm:

<form [formGroup]="myForm">

Note that name and email are controls in the form that needs binding using formControlName :

<input type="text" name="name" formControlName="name">

you have to import both, import { FormsModule } from '@angular/forms'; import { ReactiveFormsModule } from '@angular/forms'; into your corresponding module.ts file. that worked for me.

I ran into a similar scenario.

Issue is that angular v9 didn't liked @Host() any more. Fix is removing @Host() from dependency declaration in the constructor.

https://github.com/angular/angular/issues/31539

In your code formGroup is missing try this: <form [formGroup] = "">

In my case, I had forgotten to put ReactiveFormsModule to the imports section in the corresponding .spec.ts file.

Your question is very similar to this question and your code looks missing [formGroup] as it is mentioned in this question:

Angular 5: "No provider for ControlContainer"

If you try its answer, would that work for you?

Make sure you have all the below conditions correctly configured

In app.module.ts

import { ReactiveFormsModule } from '@angular/forms';

@NgModule({
  declarations: [],
  imports: [
   ReactiveFormsModule
  ],
  providers: [],
  bootstrap: []
})

In app.component.ts

userForm:FormGroup = new FormGroup({
      'username': new FormControl(null,Validators.required),
      'password': new FormControl(null,Validators.required),
      'confirm-password': new FormControl(null,Validators.required)
})

In HTML code

<form [formGroup]="userForm">
......
</form>

I came across the same issue with Angular 9 and I already had ReactiveFormsModule and FormsModule imported.

Turns out that @Host() decorator is not working with Ivy. Only solution that helped is removing @Host() from the dependency declaration in the constructor.

Angular new Rendering engine Ivy doesn't like @Host() decorator.

if you are using Modal for Ionic

Then import this

import { FormGroup, FormControl } from '@angular/forms'; //imports

to the parent module of the modal.