Javascript calls Web Service returns error in Dynamics CRM but returns OK from an HTML file

Hi experts,

Last week the following code was returning Ok in Dynamics CRM and since yesterday it was returning Error but the Web Service still executing perfectly well and returning true at the end of the CSOM code.

Please note that the same code is returning Ok when I run it from an HTML file and I reference the same jquery library as in Dynamics CRM: 2.1.1

      $.ajax({
        url: strUrl,
        data: {
          format: 'json'
        },
        error: function(request,status,error) {
          alert('Error');
        },
        success: function(data) {
          alert('Ok');
        }
      });

Maybe an upgrade has been done in Dynamics CRM since last week.

Best regards,

Christophe