When writing entry into indexed cache I get multiple FileNotFoundExceptions in the indexer thread:

12:07:37,503 ERROR [org.hibernate.search.exception.impl.LogErrorHandler] (Hibernate Search: Index updates queue processor for index org.radargun.query.NumberObject-1) HSEARCH000058: HSEARCH000117: IOException on the IndexWriter
java.io.FileNotFoundException: No sub-file with id .prx found (fileName=_2rm.cfs files: [.tii, .fnm, .tis, .frq, .fdt, .nrm, .fdx])
        at org.apache.lucene.index.CompoundFileReader.openInput(CompoundFileReader.java:157)
        at org.apache.lucene.index.SegmentCoreReaders.<init>(SegmentCoreReaders.java:96)
        at org.apache.lucene.index.SegmentReader.get(SegmentReader.java:116)
        at org.apache.lucene.index.IndexWriter$ReaderPool.get(IndexWriter.java:696)
        at org.apache.lucene.index.IndexWriter$ReaderPool.get(IndexWriter.java:671)
        at org.apache.lucene.index.BufferedDeletesStream.applyDeletes(BufferedDeletesStream.java:200)
        at org.apache.lucene.index.IndexWriter.doFlush(IndexWriter.java:3615)
        at org.apache.lucene.index.IndexWriter.prepareCommit(IndexWriter.java:3376)
        at org.apache.lucene.index.IndexWriter.commitInternal(IndexWriter.java:3485)
        at org.apache.lucene.index.IndexWriter.commit(IndexWriter.java:3467)
        at org.apache.lucene.index.IndexWriter.commit(IndexWriter.java:3451)
        at org.hibernate.search.backend.impl.lucene.IndexWriterHolder.commitIndexWriter(IndexWriterHolder.java:158)
        at org.hibernate.search.backend.impl.lucene.IndexWriterHolder.commitIndexWriter(IndexWriterHolder.java:171)
        at org.hibernate.search.backend.impl.lucene.ExclusiveIndexWorkspaceImpl.afterTransactionApplied(ExclusiveIndexWorkspaceImpl.java:45)
        at org.hibernate.search.backend.impl.lucene.LuceneBackendQueueTask.applyUpdates(LuceneBackendQueueTask.java:124)
        at org.hibernate.search.backend.impl.lucene.LuceneBackendQueueTask.run(LuceneBackendQueueTask.java:67)
        at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)
        at java.util.concurrent.FutureTask.run(FutureTask.java:262)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
        at java.lang.Thread.run(Thread.java:745)