: org.apache.solr.common.SolrException: Error Instantiating : QueryResponseWriter, solr.VelocityResponseWriter is not a : org.apache.solr.response.QueryResponseWriter
If you started with the example solr configuration from Solr 3.5, it contains refrences to the solr.VelocityResponseWriter which is packaged in a "contrib" jar (ie: not included directly in the solr.war file) you will see refrences to solr.VelocityResponseWriter in your solrconfig.xml that you can delete, or you can fix the paths refrenced in the <lib /> directives of your solrconfig.xml file to point at where those contrib jars are actually located on your system. -Hoss
