"Missing" is different then "null" ... in truth what i suspect yo uare doing is indexing something like this...
<field name="pubdate"></field> ...that is an empty string (""), and the error is because an empty string can't be converted to a number : when i indexed a doc with null value of this field, an error happened: : : SEVERE: org.apache.solr.common.SolrException: Error while creating field : 'pubdate{type=slong,properties=indexed,stored,omitNorms,sortMissingLast}' : from value '' : : and slong type defined as below: : <fieldType name="slong" class="solr.SortableLongField" : sortMissingLast="true" omitNorms="true"/> : : since it's permitted that this field is null when sorting, why not when : indexing? -Hoss