title: org.apache.solr.common.SolrException: ERROR: [doc=SOMEURL] unknown field ''
body: <p>Hi I am getting this exception and I've exhausted all the possible settings that I could think of.</p>
  
  <pre><code>org.apache.solr.common.SolrException: ERROR: [doc=SOMEURL] unknown field ''
  </code></pre>
  
  <p>The problem is <strong>field ''</strong> - the quotation marks are empty so I don't know what causes the problem.</p>
  
  <p>Does anybody had the same problem? I will help me a lot.</p>
  
  <p>Some informations:</p>
  
  <ul>
  <li>Nutch version 2.1 </li>
  <li>Solr version 1.5</li>
  <li>Hbase as a data storage
  -Tomcat6 for Solr running</li>
  </ul>
  
  <p>In code have just this: </p>
  
  <pre><code>nutchDocument.add("my_key",stringValue);
  </code></pre>
  
  <p>I have checked Solr's schema.xml, Nutch's schema.xml and also Nutch solr-mapping.xml (I am sure in the right directories) in each is "my_key" written in the right way.</p>
  
  <p>Thanks for help</p>