<form method="POST" [formGroup]="form" #form="ngForm" >
                    <label for="nombre">Nombre</label>
                    <input
                        [formControlName]="nombre"
                        [formGroupName]="form"
                        placeholder="Nombre:"
                        type="text"
                        [(ngModel)]="usuario.nombre"
                        name="nombre"/>
                    <input type="hidden" [(ngModel)]="usuario.id" name="id" value=0 />
                    <label for="apellidos">Apellidos</label>
                    <input
                        placeholder="Apellidos:"
                        type="text"
                        [(ngModel)]="usuario.apellidos"
                        name="apellidos"
                        formControlName="apellidos"
                        formGroupName="form"/>
                    <label for="email">Email(Login)</label>
                    <input
                        placeholder="Email:"
                        type="text"
                        [(ngModel)]="usuario.email"
                        name="email"
                        formControlName="email"
                        formGroupName="form"/>
                    <label for="administrador">Administrador</label>
                    <input
                        type="checkbox"
                        id="administrador"
                        name="administrador"
                        [(ngModel)]="usuario.administrador"
                        formControlName="administrador"
                        formGroupName="form"/>
                    <hr />
                    <a class="btn btn-default btn-block" (click)="enviar()">Enviar!</a>
                    <a class="btn btn-default btn-block" (click)="volver()">Cancelar</a>
                </form>

import { UsuariosService } from '../../services/usuarios.service';
import { Router } from '@angular/router';
import { Usuario } from '../../interfaces/usuario';
import {Component, ElementRef, ViewChild} from '@angular/core';
import {FormBuilder, FormGroup, Validators} from "@angular/forms";
@Component({
  selector: 'app-gusuarios',
  templateUrl: './gusuarios.component.html',
  styleUrls: ['./gusuarios.component.css']
  })

export class GUsuariosComponent implements OnInit {
  title = 'Gestión de usuarios';
  form: FormGroup;
  static readonly clase:string = 'GUsuariosComponent';
  submitted = false;
  usuarios:any = [];
  usuario:Usuario = new Usuario();
  error:string = '';

  constructor(private usuariosService:UsuariosService, private router:Router,private fb: FormBuilder){
    console.log(GUsuariosComponent.clase+".constructor. entra");
    usuariosService.getUsuarios(this);
    console.log(GUsuariosComponent.clase+".constructor. sale");
  };
  ngOnInit() {
    console.log(GUsuariosComponent.clase+".ngOnInit. entra");
    this.form= this.fb.group({
      nombre: ['', Validators.required],
      apellidos: [''],
      email: ['' [Validators.required, Validators.email]],
      administrador: [0, Validators.required]
    })
    console.log(GUsuariosComponent.clase+".ngOnInit. sale");
  }
  modificar(index:number){
    this.usuario=this.usuarios[index];
  }
  eliminar(index:number){
    this.usuariosService.eliminarUsuario(this, this.usuarios[index].id, index);
  }
  enviar(){
    this.submitted = true;

    // stop here if form is invalid
    if (this.form.invalid) {
        return;
    }
    this.usuariosService.guardarUsuario(this, document);
  }
  volver(){
    this.router.navigate(['admin']);
  }
    // convenience getter for easy access to form fields
  get f() { return this.form.controls; }

}

ERROR TypeError: this.form._updateTreeValidity is not a function
at FormGroupDirective.push../node_modules/@angular/forms/fesm5/forms.js.FormGroupDirective._updateDomValue (forms.js:5397)
at FormGroupDirective.push../node_modules/@angular/forms/fesm5/forms.js.FormGroupDirective.ngOnChanges (forms.js:5240)
at checkAndUpdateDirectiveInline (core.js:22095)
at checkAndUpdateNodeInline (core.js:23363)
at checkAndUpdateNode (core.js:23325)
at debugCheckAndUpdateNode (core.js:23959)
at debugCheckDirectivesFn (core.js:23919)
at Object.eval [as updateDirectives] (GUsuariosComponent.html:18)
at Object.debugUpdateDirectives [as updateDirectives] (core.js:23911)
at checkAndUpdateView (core.js:23307)