Hello,
Only one word can resolve the problem : [+ef_wrapper+]. Include this in lang files : francais-utf8.inc.php and francais.inc.php in the item "ef_validation_message" like that :
$_lang["ef_validation_message"] = "<strong>Des erreurs ont été detectées dans le formulaire :</strong> [+ef_wrapper+] <br />";
Frenchies will thank you to fix that bug, and I very thank you Tobyl for this excellent snippet
bests regards