text: Q:
  
  Symfony form_login does not work, but http_basic does
  
  I'm trying to implement a login function in my Symfony2 application, using the built-in login functionnality from Symfony.
  I can access the /login page fine, but when I type my username and password, and hit login, it just brings me back to the /login page, without any error message.
  If I try to connect with the wrong username and/or password, or none, the same thing happens: I get redirected to /login with no error message.
  I tried to connect using http_basic, and it worked. So I suppose my users provider is good, but I don't get what prevents the login from working.
  login.html.twig
  {% extends "::layout.html.twig" %}
  
  {% block title %}Login{% endblock %}
  
  {% block stylesheets %}
      {{ parent() }}
      {% stylesheets 'bundles/seinput/css/login/*' filter='cssrewrite' %}
      <link rel="stylesheet" type="text/css" charset="UTF-8" media="all" href="{{ asset_url }}"/>
      {% endstylesheets %}
  {% endblock %}
  
  {% block body %}
      <form action="{{ path('login') }}" method="post">
          <div class="field">
              <label for="username">Username:</label>
              <input type="text" id="username" name="_username" value="{{ last_username }}" />
          </div>
          <div class="field">
              <label for="password">Password:</label>
              <input type="password" id="password" name="_password" />
          </div>
          <div class="form-button">
              <button class="btn btn-success" type="submit">login</button>
          </div>
      {% if error %}
          <div>{{ error.messageKey|trans(error.messageData, 'security') }}</div>
      {% else %}
          <div>No error</div>
      {% endif %}
          <input type="hidden" name="_target_path" value="/" />
      </form>
  {% endblock %}
  
  edit: Now that the answer is provided, and since the error comes from a single line in the twig file, I removed the other files, to make the question more readable to future readers.
  
  A:
  
  I see that your form have and action that points to login URL, ¿you can try to modify this to login_check?
  I think that your problem is near here
  <form action="{{ path('login_check') }}" method="post">
  
  