title: Cesium GeoServer error : An error occurred in "WebMapServiceImageryProvider": Failed to obtain image tile
body: <p>I'm trying to run Cesium with GeoServer in order to learn and practice things I need to do.
  I have installed and downloaded everything needed but when I am trying to run the basic examples from Cesium \ GeoServer I get the error mentioned above.
  <br>
  My code is the following : </p>
  
  <pre><code>    &lt;script&gt;
      var viewer = new Cesium.Viewer('cesiumContainer');
      var provider = new Cesium.WebMapServiceImageryProvider({
          url: 'http://localhost:8080/geoserver/wms',
          layers: '',
          proxy: new Cesium.DefaultProxy('/proxy/')
      });
  
      viewer.imageryLayers.addImageryProvider(provider);
  &lt;/script&gt;
  </code></pre>
  
  <p>and the error is </p>
  
  <pre><code>Failed to load resource: the server responded with a status of 404 (Not Found) Cesium.js:21186 An error occurred in "WebMapServiceImageryProvider": Failed to obtain image tile X: 1 Y: 0 Level: 0.
  </code></pre>
  
  <p>when removing the proxy field, I get this error</p>
  
  <pre><code>Image from origin 'http://localhost:8080' has been blocked from loading by Cross-Origin Resource Sharing policy: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://localhost:64365' is therefore not allowed access. Cesium.js:21186 An error occurred in "WebMapServiceImageryProvider": Failed to obtain image tile X: 0 Y: 0 Level: 0.
  </code></pre>
  
  <p>I have googled it and tried to configure the web.xml file according to the CORS IIS7 (running VS15) guide but with no luck.</p>
  
  <p><br>
  Any chance someone know what can I do ?</p>