Getting the error: This field is required when update user

Question

I'm trying to update a user profile using two forms the problem is that when I click to update I get the following error:

“<ul class="errorlist">
<li>username<ul class="errorlist"><li>This field is required.</li>
</ul>
 ”

My model module is the following:

# user.models
from django.contrib.auth.models import AbstractUser
from django.db import models

from model_utils.models import TimeStampedModel
from localflavor.br.models import BRPostalCodeField, BRStateField, BRCNPJField, BRCPFField


class User(AbstractUser):
    class Roles(models.IntegerChoices):
        SUPER = 0
        COMPANY = 1
        UNITY = 2
        STAFF = 3

    picture = models.ImageField(blank=True, null=True)
    role = models.IntegerField(choices=Roles.choices, default=Roles.STAFF)


class Staff(TimeStampedModel):
    user: User = models.OneToOneField(User, null=True, on_delete=models.CASCADE)
    unity = models.ForeignKey(Unity, related_name="staff", on_delete=models.CASCADE)
    cpf = BRCPFField("CPF")

    class Meta:
        verbose_name: str = 'Staff'
        verbose_name_plural: str = 'Staff'
        ordering = ("-created",)

    def __str__(self):
        if f"{self.user.first_name} {self.user.last_name}".strip():
            return f"{self.user.first_name} {self.user.last_name}"
        return str(self.user.username)

And my user forms looks like:

#user.forms

class UserModelForm(forms.ModelForm):

    class Meta:
        model = User
        fields = ['username', 'first_name', 'last_name', 'email', 'is_active']


class StaffModelForm(forms.ModelForm):
    class Meta:
        model = Staff
        fields = ['cpf', 'unity']
        widget = {
            'cpf': forms.TextInput(attrs={'class': "form-control", 'placeholder': 'Primeiro Nome', }),
            'unity': forms.EmailInput(attrs={'class': "form-control", 'placeholder': '[email protected]', }),
        }

with the following view:

#views
…
def update_staff(request: HttpRequest, pk: int) -> HttpResponse:
    instance: Staff = get_object_or_404(Staff, pk=pk)  # get staff instance
    template_name = 'pages/staff_update_form.html'  # use this template
    if request.method == "POST":
        profile_form = user_forms.StaffModelForm(request.POST, instance=instance)
        user_form = user_forms.UserModelForm(request.POST, request.FILES, instance=instance.user)

        print(user_form.is_valid())
        print(user_form.errors)
        print(profile_form.is_valid())
        if user_form.is_valid() and profile_form.is_valid():
            user_form.save()
            profile_form.save()
            messages.success(request, 'Your profile is updated successfully')
            return redirect(to='pages:dashboard')

    context = dict(profile_form=user_forms.StaffModelForm(instance=instance),
                   user_form=user_forms.UserModelForm(instance=instance.user))
    return render(request, template_name=template_name, context=context)

Print output:

False
<ul class="errorlist"><li>username<ul class="errorlist"><li>This field is required.</li></ul
></li></ul>
True

and HTML:

{% load crispy_forms_tags %}
{% if user_form.errors %}
<div class="alert alert-danger alert-dismissible" role="alert">
    <div id="form_errors">
        {% for key, value in user_form.errors.items %}
        <strong>{{ value }}</strong>
        {% endfor %}
    </div>
    <button type="button" class="close" data-dismiss="alert" aria-label="Close">
        <span aria-hidden="true">&times;</span>
    </button>
</div>
{% endif %}
<div class="py-5 text-center">
    <span class="material-icons" style="height: 48px; width: auto; font-size: 48px;">people_alt</span>
    <h1 class="h3 mb-3 fw-normal">Atualize aqui os dados do usuário!</h1>
</div>
<form class="form-signin" method="POST" enctype="multipart/form-data">

    <div class="form-group">
        <div class="row g-8 my-auto mx-auto" style="padding-left: 12%; padding-right: 12%;">
            <div class="col-md-8 col-lg-12">
                {% crispy profile_form %}
            </div>
        </div>
        <div class="row g-8 my-auto mx-auto" style="padding-left: 12%; padding-right: 12%;">
            <div class="col-md-8 col-lg-12">
                {% crispy user_form %}
            </div>
        </div>
        <div class="col-md-12 col-lg-12">
            <br>
            <div class="modal-footer">

                <a href="{% url 'pages:dashboard' %}" class="btn btn-warning mb-2 type='button'">Cancel</a>
                <button class="btn btn-primary mb-2" type="submit">Update</button>
            </div>
        </div>


    </div>

</form>

<div class="py-5 text-center">
    <p class="mt-5 mb-3 text-muted">&copy; 2022-2023</p>
</div>

So I have no idea what the source of this problem is. Everything seems fine to me, can anyone help me?