Fix Prestashop Webservice Error

Hello everyone,

I'm looking for someone to fix errors on prestashop webservice.

if the debug mode is disabled i get this error message :
<error>
<code>5</code>
<message>
[PHP Notice #8] Undefined index: description (data/www/classes/webservice/WebserviceOutputBuilder.php, line 319)
</message>
</error>

and when i activate the debug mode only Get method works but Mthod POST and PUT throws :

XML error : String could not be parsed as XML