java.lang.NullPointerException (500)

The requested URL /var/search/pool/manager-viewer.json resulted in an error in org.sakaiproject.nakamura.search.solr.SolrSearchServlet.
Request Progress:

      0 (2011-12-09 16:08:26) TIMER_START{Request Processing}
      0 (2011-12-09 16:08:26) COMMENT timer_end format is {<elapsed msec>,<timer name>} <optional message>
      0 (2011-12-09 16:08:26) LOG Method=GET, PathInfo=/var/search/pool/manager-viewer.json
      0 (2011-12-09 16:08:26) TIMER_START{ResourceResolution}
      6 (2011-12-09 16:08:26) TIMER_END{6,ResourceResolution} URI=/var/search/pool/manager-viewer.json resolves to Resource=JcrNodeResource, type=sakai/solr-search, superType=null, path=/var/search/pool/manager-viewer
      6 (2011-12-09 16:08:26) LOG Resource Path Info: SlingRequestPathInfo: path='/var/search/pool/manager-viewer', selectorString='null', extension='json', suffix='null'
      6 (2011-12-09 16:08:26) TIMER_START{ServletResolution}
      6 (2011-12-09 16:08:26) TIMER_START{resolveServlet(JcrNodeResource, type=sakai/solr-search, superType=null, path=/var/search/pool/manager-viewer)}
      6 (2011-12-09 16:08:26) TIMER_END{0,resolveServlet(JcrNodeResource, type=sakai/solr-search, superType=null, path=/var/search/pool/manager-viewer)} Using servlet org.sakaiproject.nakamura.search.solr.SolrSearchServlet
      6 (2011-12-09 16:08:26) TIMER_END{0,ServletResolution} URI=/var/search/pool/manager-viewer.json handled by Servlet=org.sakaiproject.nakamura.search.solr.SolrSearchServlet
      6 (2011-12-09 16:08:26) LOG Applying Requestfilters
      6 (2011-12-09 16:08:26) LOG Calling filter: org.apache.sling.engine.impl.debug.RequestProgressTrackerLogFilter
      6 (2011-12-09 16:08:26) LOG Calling filter: org.sakaiproject.nakamura.cluster.ClusterTrackingFilter
      6 (2011-12-09 16:08:26) LOG Calling filter: org.sakaiproject.nakamura.batch.RequestEventsFilter
      6 (2011-12-09 16:08:26) TIMER_START{org.sakaiproject.nakamura.search.solr.SolrSearchServlet#0}
    125 (2011-12-09 16:08:26) TIMER_START{handleError:status=500}
    127 (2011-12-09 16:08:26) TIMER_END{2,handleError:status=500} Using handler org.apache.sling.servlets.resolver.internal.defaults.DefaultErrorHandlerServlet
    138 (2011-12-09 16:08:26) TIMER_END{138,Request Processing} Dumping SlingRequestProgressTracker Entries