Authentification probleme Symfony 4

I have a little problem with my Symfony 4 login page. When users submits the form, the following error appears:

Notice: A non well formed numeric value encountered

and yet when I go to the data base the login is there, the password is there too (hash it out of course) and despite this it doesn't work.

this is the controller

<?php

namespace App\Controller ;

use Symfony\Bundle\FrameworkBundle\Controller\AbstractController;
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\Routing\Annotation\Route;
use App\Entity\User ;

//Class pour authentification
use Symfony\Component\Security\Http\Authentication\AuthenticationUtils ;


class SecurityController extends AbstractController
{

  /**
  * @Route("/login" , name="login")
  */
  public function login(AuthenticationUtils $authentication)
  {
    $error = $authentication->getLastAuthenticationError();

    $lastUsername = $authentication->getLastUsername();

    return $this->render('Authentification/login.html.twig' ,[
      'error'         => $error,
      'last_username' => $lastUsername,
      ]) ;
  }
}

security.yaml file:

security:
    providers:
        from_database:
            entity:
                class: App\Entity\User
                property: username

    firewalls:
        dev:
            pattern: ^/(_(profiler|wdt)|css|images|js)/
            security: false
        main:
            anonymous: lazy
            form_login:
                remember_me: true
                check_path: /login

            logout :
                path: /logout
                target: /

    access_control: 
        - { path: ^/admin, roles: ROLE_ADMIN } #cane_loader

    encoders:
        App\Entity\User:
          algorithm: bcrypt
          cost :  14

form login :

{% extends 'baseConnection.html.twig' %}

{% block title %}Se Connecter{% endblock %}

{% block body %}
<div class="container">

  <h3>Page de Connection de l'application CUMA le PROGRES</h3>

  <p class="btn float-right color-br" onclick="window.history.back();">Retour</p>

  {% if error %}

  <div class="alert alert-danger">

    {% if error %}

    {{ error.messageKey | trans(error.messagedata ,  'security') }}

    {% endif %}

  </div>

  {% endif %}

  <form  action="{{  path('login')}}" method="post">
    <div class="form-group">
      <label for="username">Nom d'utilisateur</label>
      <input type="text" id="username" name="_username" class="form-control" placeholder="Vôtre nom d'utilisateur est du style:    Prénom.Nom" value="{{ last_username }}">
    </div>
      <div class="form-group">

          <label for="password">Mot de passe</label>

          <input type="password" id="password" name="_password" class="form-control" placeholder="Vôtre mot de passe ..... ( en cas d'oublie aller voir Fabien ABISUR )">
      </div>
      <button type="submit" class="btn color-br">Se Connecter</button>
    </form>
</div>
{% endblock %}