An error occurred while attaching module (Dynamicweb.Frontend.Content)

System.NullReferenceException: Object reference not set to an instance of an object.
   at Lucene.Net.Util.CloseableThreadLocal`1.Get() in d:\Lucene.Net\FullRepo\trunk\src\core\Util\CloseableThreadLocal.cs:line 69
   at Lucene.Net.Index.SegmentReader.Document(Int32 n, FieldSelector fieldSelector) in d:\Lucene.Net\FullRepo\trunk\src\core\Index\SegmentReader.cs:line 1193
   at Dynamicweb.Indexing.Lucene.LuceneIndexProvider.DoSearch(Int32 skip, ScoreDoc[] docs, IndexSearcher searcher, FieldDefinitionBase[] fields)
   at Dynamicweb.Indexing.Lucene.LuceneIndexProvider.SearchInternal(IQuery query, QuerySettings settings)
   at Dynamicweb.Indexing.Querying.QueryService.Query(IQuery query, QuerySettings settings)
   at Dynamicweb.QueryPublisher.Frontend.GetContent()
   at Dynamicweb.Frontend.Content.GetModuleOutput(Paragraph paragraph, PageView pageview)