问禁止(403) CSRF验证失败。当我点击提交按钮时，请求中止

EN

    <div class="grad"></div>
    <div class="header">
    <div>MLAT<span>SI</span></div>
    </div>
    <form action="{{views.login_user}}" method="POST">{% csrf_token %}
    <div class="login">
    <img src="{% static "img/Airplane.png" %}">
    <div id="h" class="home">
    <input type="text" placeholder="Login" name="username" value="">
    <input type="password" placeholder="Mot de passe" name="password" value="">
    <input style="float: left; width: 173px" type="submit" value="Log in" > 
    <input formaction="/form_registration.html/" style="float: right; width: 173px" type="submit" value="Register">

def login_user(request):
    username = request.POST.get("username")
    password = request.POST.get("password")
    user = authenticate(username=username, password=password)
    if user is not None and user.is_active:
        login(request, user)
        return HttpResponse("You're logged in.")
    else:
        return HttpResponse("Your username and password didn't match.")