Wordperss admin-ajax.php error 400 Bad Request - php

Question

I can't find where this error 400 comes from?
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I'm trying to create a form to post a custom post type through Ajax.
Here is the form in front office:
<form id="form_info" enctype="multipart/form-data">
<div class="form-group">
<label for="titre_info">Titre *</label>
<input type="text" id="titre_info" name="titre_info" placeholder="Titre" />
</div>
<div class="form-group">
<label for="message_info">Message *</label>
<textarea id="message_info" name="message_info" placeholder="Message"></textarea>
</div>
<div class="form-group">
<label for="img_info">Visuel (facultatif)</label>
<input type="file" id="img_info" name="img_info" />
</div>
<div style="text-align:center;">
<input type="submit" id="submit_info" name="submit_info" value="Poster" />
<div class="status_info"></div>
</div>
</form>
Here is my JQuery :
$('#form_info').on('submit',function(e){
$('.status_info').hide();
e.preventDefault();
var validForm = true;
var title = $("#titre_info").val();
var message = $('#message_info').val();
var image = $('#img_info').prop('files');
if(title=="" || message==""){
validForm=false;
}
if(validForm) {
$('.status_info').show().html("<p>Envoi du message en cours...</p>");
$.ajax({
type: 'POST',
dataType: 'json',
contentType: false,
processData: false,
url: '/wordpress/wp-admin/admin-ajax.php',
data: {
'action': 'addinfo',
'titre': title,
'message': message,
'image': image
},
success: function (data) {
$('.status_info').show().html("<p class='success'>Merci de votre ajout</p>");
setTimeout(function(){location.reload();},750);
}
})
} else {
$('.status_info').show().html("<p class='error'>Merci de compléter les champs obligatoires</p>");
$("#titre_info").addClass('error');
$("#message_info").addClass('error');
}
});
Here is my function PHP :
add_action( 'wp_ajax_nopriv_addinfo', 'AddInfo' );
add_action( 'wp_ajax_addinfo', 'AddInfo' );
function AddInfo(){
$titre=$_POST['titre'];
$message=$_POST['message'];
$image=$_POST['image'];
$my_post = array(
'post_title' => $titre,
'post_content' => $message,
'post_status' => 'publish',
'post_type' => 'annonce',
);
$my_new_post = wp_insert_post($my_post);
echo json_encode(array('post'=>$my_new_post,"status"=>"succes"));
die();
}
It used to work but I then try to add the file upload and then everything skratch. Now returned to basic creating simple text post_type I'm stuck with my Error 400 Bas Request on url admin-ajax.php
I also tried to add the security none, same problem.
I tried to use ajax_object to create the ajax url but same probleme.
The Php function change this way :
add_action('init','ajax_register_action');
function ajax_register_action() {
wp_register_script('ajax-addinfo-script', get_stylesheet_directory_uri() . '/ajax-addinfo-script.js', array('jquery'));
wp_localize_script('ajax-addinfo-script', 'ajax_addinfo_object', array('ajaxurl' => admin_url('admin-ajax.php'),));
wp_enqueue_script('ajax-addinfo-script');
add_action( 'wp_ajax_nopriv_addinfo', 'AddInfo' );
add_action( 'wp_ajax_addinfo', 'AddInfo' );
}
And the jQuery call the ajax url this way :
url: ajax_addinfo_object.ajaxurl,
I checked a lot of StackOverflow and Google questions about this error but still can't find where it comes from.
If you can see what's wrong that will be a gret relief!
Thanks a lot!