Can't solve "OperationNotSupported" error on WFS GetFeature request

Question

I'm working on a web map viewer using OpenLayers, ExtJS, GeoExt and GXP. I've added a LayerTree (gxp_layertree) that shows layers from various WMS servers from different GeoServer versions. I've also configured a FeatureManager (gxp_featuremanager) with 'autoLoadFeatures = true' and a FeatureGrid (gxp_featuregrid).

My problem appears when I click on a layer tree node and a WFS GetFeature request fires: the response is always "OperationNotSupported" "No such operation WFS null WfsDispatcher".

I've checked the XML body content with the embedded 'demo requests' in GeoServer and it's OK. That is:

<wfs:GetFeature xmlns:wfs="http://www.opengis.net/wfs" service="WFS" version="1.1.0" maxFeatures="100" xsi:schemaLocation="http://www.opengis.net/wfs http://schemas.opengis.net/wfs/1.1.0/wfs.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <wfs:Query typeName="feature:mce_prov_escuelas" srsName="EPSG:4326" xmlns:feature="mce">
    <ogc:Filter xmlns:ogc="http://www.opengis.net/ogc">
      <ogc:BBOX>
         <ogc:PropertyName>the_geom</ogc:PropertyName>
         <gml:Envelope xmlns:gml="http://www.opengis.net/gml" srsName="EPSG:4326">
            <gml:lowerCorner>-62.406926496825 -26.770412516161</gml:lowerCorner>
            <gml:upperCorner>-57.557744198657 -22.49170214764</gml:upperCorner>
         </gml:Envelope>
      </ogc:BBOX>
     </ogc:Filter>
  </wfs:Query>
</wfs:GetFeature>

It's a POST request and here's a copy of the headers (from Firebug):

REQUEST HEADERS
Accept      text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Encoding gzip, deflate
Accept-Language es-ar,es;q=0.8,en-us;q=0.5,en;q=0.3
Content-Length  723
Content-Type    application/xml; charset=UTF-8
Host        localhost
Referer     http://localhost/visor/index.html
User-Agent      Mozilla/5.0 (X11; Ubuntu; Linux i686; rv:24.0) Gecko/20100101 Firefox/24.0
X-Requested-With    XMLHttpRequest

Any clue?

I've tried everything I know and Googled it without many results.

Answer 1

I had problems with "Content-Type: application/xhtml+xml" (all of a sudden). I changed it to text/html and for some reason it works. I didn't dig deeper into it but possibly it's connected...