add_error() takes exactly 2 arguments (3 given)

/home/victor/Documents/Codigos/website/users/views.py in post
    if form.is_valid(): ...
▶ Local vars
/home/victor/Documents/Codigos/website/users/forms.py in is_valid
    if not super(RegisterUserForm, self).is_valid(): ...
▶ Local vars

Não to sabendo onde arrumar o erro e oq ele significa

users/views.py

from django.shortcuts import render
from django.http import HttpResponseRedirect
from django.urls import reverse
from django.views.generic.base import View
from django.contrib.auth.models import User
from .forms import *
from curriculum.models import Profile

class RegisterUserView(View):
  template = 'users/register.html'

  def get(self, request):
    return render(request, self.template)

  def post(self, request):
    form = RegisterUserForm(request.POST)
    if form.is_valid():
      user = User.objects.create_user(form.data['username'], form.data['email'], form.data['password'])
      profile = Profile(first_name=form.data['name'],
                        user = user)
      profile.save()
      return HttpResponseRedirect(reverse('curriculum:home', args=(profile.id,)))
    return render(request, self.template, {'form': form})

users/forms.py

from django import forms
from django.contrib.auth.models import User

class RegisterUserForm(forms.Form):
  name = forms.CharField(required=True)
  username = forms.CharField(required=True)
  email = forms.EmailField(required=True)
  password = forms.CharField(required=True)

  def is_valid(self):
    valid = True
    if not super(RegisterUserForm, self).is_valid():
      self.add_error('Please check the information provided')
      valid = False

    user_exists = User.objects.filter(username=self.data['username']).exists()
    if user_exists:
      self.add_error('User already exists')
      valid = False

    return valid

  def add_error(self, message):
    errors = self._errors.setdefault(forms.forms.NON_FIELD_ERRORS, forms.utils.ErrorList())
    errors.append(message)

users/register.html

{% extends 'users/base.html' %}
{% block body %}
  <form class="form-signin" action="{% url 'users:register' %}" method="post">
    {% csrf_token %}
    <h2 class="form-signin-heading">Cadastro</h2>
    <input id="id_name" name="name" type="text" class="form-control" placeholder="name" value="{{form.name.value}}" required autofocus/>
    <input id="id_username" name="username" type="text" class="form-control" placeholder="Username" value="{{form.username.value}}" required />
    <input id="id_email" name="email" type="text" class="form-control" placeholder="Email" value="{{form.email.value}}" required />
    <input id="id_password" name="password" type="password" class="form-control" placeholder="Password" required />
    <hr />
    {% if form.erros %}
      <div class="alert alert-danger">
        <button type="button" class="close" data-dismiss="alert" aria-hidden="true">&times;</button>
        {{form.non_field_errors}}
      </div>
    {% endif %}
    <button class="btn btn-lg btn-primary btn-block" type="submit">Register</button>
  </form>
{% endblock %}