hi! <br><br>i did some change in WMSCapabilitiesLoader.js to fire exception on bad request.<br>i did some tests and it&#39;s seems to work. <br><br><br>Ext.override(GeoExt.tree.WMSCapabilitiesLoader, {<br><br>    processResponse : function(response, node, callback, scope){<br>
        var capabilities = new OpenLayers.Format.WMSCapabilities().read(<br>            response.responseXML || response.responseText);<br><br>        if(!capabilities.capability){<br>            scope.loading = false;<br>
            node.wmsbrowser.fireEvent(&#39;getcapabilitiesfail&#39;);<br>        }<br>        else{            <br>            this.processLayer(capabilities.capability,<br>                capabilities.capability.request.getmap.href, node);<br>
            if (typeof callback == &quot;function&quot;) {<br>                callback.apply(scope || node, [node]);<br>            }<br>        }<br>    }<br>});<br><br>Marc-André Trottier<br>