ngModel cannot be used to register form controls with a parent formGroup directive
The answer is right on the error message,you need to indicate that it's standalone and therefore it doesn't conflict with the form controls:
[ngModelOptions]="{standalone: true}"
Expanding on @Avenir Çokaj's answer
Being a novice even I did not understand the error message clearly at first.
What the error message indicates is that in your formGroup you have an element that doesn't get accounted for in your formControl. (Intentionally/Accidentally)
If you intend on not validating this field but still want to use the ngModel on this input element please add the flag to indicate it's a standalone component without a need for validation as mentioned by @Avenir above.
OK, finally got it working: see https://github.com/angular/angular/pull/10314#issuecomment-242218563
In brief, you can no longer use name attribute within a formGroup, and must use formControlName instead