Example:


<div [formGroup]="myGroup">
  <input formControlName="firstName">
</div>

In your class:

this.myGroup = new FormGroup({
   firstName: new FormControl()
});
at Function.ReactiveErrors.missingFormException (forms.js:6347)
at FormGroupDirective._checkFormPresent (forms.js:6852)
at FormGroupDirective.ngOnChanges (forms.js:6623)
at checkAndUpdateDirectiveInline (core.js:12358)
at checkAndUpdateNodeInline (core.js:13886)
at checkAndUpdateNode (core.js:13829)
at debugCheckAndUpdateNode (core.js:14722)
at debugCheckDirectivesFn (core.js:14663)
at Object.eval [as updateDirectives] (EditVisitanteDialogComponent.html:10)
at Object.debugUpdateDirectives [as updateDirectives] (core.js:14648)

<div class="dialog-content-wrapper">
    <mat-toolbar matDialogTitle class="mat-accent m-0">
        <mat-toolbar-row fxLayout="row" fxLayoutAlign="space-between center">
            <span class="title dialog-title">Editar visitante</span>
            <button mat-button class="mat-icon-button" (click)="dialogRef.close()" aria-label="Close dialog">
                <mat-icon>close</mat-icon>
            </button>
        </mat-toolbar-row>
    </mat-toolbar>
    <form name="form" [formGroup]="editForm" #f="ngForm">
        <div mat-dialog-content class="m-0 p-24" fusePerfectScrollbar>
            <div fxLayout="row" fxLayoutAlign="start start">
                <mat-icon class="mr-12 mt-12">label_outline</mat-icon>
                <mat-form-field class="mr-16">
                    <mat-select placeholder="Documento" formControlName="documento">
                        <mat-option value="option">Option</mat-option>
                    </mat-select>
                </mat-form-field>
                <mat-form-field>
                    <input matInput placeholder="Número" formControlName="numDocumento">
                </mat-form-field>
            </div>

            <div fxLayout="row" fxLayoutAlign="start start">
                <mat-icon class="mr-12 mt-12">account_circle</mat-icon>
                <mat-form-field fxFlex>
                    <input formControlName="nome" placeholder="Nome do Visitante" matInput required>
                </mat-form-field>
            </div>

            <div fxLayout="row" fxLayoutAlign="start start">
                <mat-icon class="mr-12 mt-12">group</mat-icon>
                <mat-form-field fxFlex>
                    <mat-select placeholder="Intenção" formControlName="motivoVisita">
                        <mat-option value="option">Familiar</mat-option>
                        <mat-option value="option">Particular</mat-option>
                        <mat-option value="option">Prestado de Serviço</mat-option>
                    </mat-select>
                </mat-form-field>
            </div>

            <div fxLayout="row" fxLayoutAlign="start start">
                <mat-icon class="mr-12 mt-12">lock_open</mat-icon>
                <mat-form-field fxFlex>
                    <mat-select placeholder="Autorização" formControlName="tipoAutorizacao">
                        <mat-option value="option">Lorem ipsum...</mat-option>
                    </mat-select>
                </mat-form-field>
            </div>

            <div fxLayout="row" fxLayoutAlign="start start">
                <div fxLayout="column">
                    <p>Quando?</p>
                    <mat-radio-group formControlName="periodoAutorizacao">
                        <mat-radio-button value="hoje">Hoje</mat-radio-button>
                        <mat-radio-button value="semanal" class="ml-8">Semanal</mat-radio-button>
                        <mat-radio-button value="periodo" class="ml-8">Período</mat-radio-button>
                    </mat-radio-group>

                    <div id="periodo" fxLayout="row" fxLayoutAlign="space-evenly start">
                        <mat-form-field fxFlex="45">
                            <input matInput [matDatepicker]="picker" placeholder="De" formControlName="periodoDe">
                            <mat-datepicker-toggle matSuffix [for]="picker"></mat-datepicker-toggle>
                            <mat-datepicker #picker></mat-datepicker>
                        </mat-form-field>
                        <mat-form-field fxFlex="45">
                            <input matInput [matDatepicker]="myDatepicker" placeholder="Até" formControlName="periodoAte">
                            <mat-datepicker-toggle matSuffix [for]="myDatepicker"></mat-datepicker-toggle>
                            <mat-datepicker #myDatepicker></mat-datepicker>
                        </mat-form-field>
                    </div>

                    <div id="semanal">
                        <mat-checkbox formControlName="diaSem1">Seg</mat-checkbox>
                        <mat-checkbox formControlName="diaSem2">Ter</mat-checkbox>
                        <mat-checkbox formControlName="diaSem3">Qua</mat-checkbox>
                        <mat-checkbox formControlName="diaSem4">Qui</mat-checkbox>
                        <mat-checkbox formControlName="diaSem5">Sex</mat-checkbox>
                        <mat-checkbox formControlName="diaSem6">Sáb</mat-checkbox>
                        <mat-checkbox formControlName="diaSem7">Dom</mat-checkbox>
                    </div>
                </div>
            </div>

            <div>
                <mat-form-field fxFlex>
                    <textarea matInput placeholder="Observação" formControlName="observacao"></textarea>
                </mat-form-field>
            </div>


        </div>
        <div mat-dialog-actions class="m-0 p-16" fxLayout="row" fxLayoutAlign="space-between center">
            <button mat-raised-button class="save-button mat-accent" aria-label="SAVE">
                SALVAR
            </button>

            <button mat-button class="mat-icon-button" aria-label="Delete" matTooltip="Excluir">
                <mat-icon>delete</mat-icon>
            </button>

        </div>
    </form>
</div>