Raised exception while starting the application. Fix the error and restart.

Message
java.nio.file.NoSuchFileException: /data_nfs/geonetwork_data/index/taxonomy/_7u.si
Handler
org.fao.geonet.Geonetwork
Exception
java.lang.RuntimeException: java.nio.file.NoSuchFileException: /data_nfs/geonetwork_data/index/taxonomy/_7u.si
Stack
java.lang.RuntimeException: java.nio.file.NoSuchFileException: /data_nfs/geonetwork_data/index/taxonomy/_7u.si
	at org.fao.geonet.kernel.search.index.LuceneIndexLanguageTracker.lazyInit(LuceneIndexLanguageTracker.java:124)
	at org.fao.geonet.kernel.search.index.LuceneIndexLanguageTracker.acquire(LuceneIndexLanguageTracker.java:187)
	at org.fao.geonet.kernel.search.SearchManager.getIndexReader(SearchManager.java:1210)
	at org.fao.geonet.kernel.search.SearchManager.getNewIndexReader(SearchManager.java:1215)
	at org.fao.geonet.kernel.search.SearchManager.getDocsChangeDate(SearchManager.java:945)
	at org.fao.geonet.kernel.DataManager.init(DataManager.java:345)
	at org.fao.geonet.Geonetwork.start(Geonetwork.java:345)
	at jeeves.server.JeevesEngine.initAppHandler(JeevesEngine.java:448)
	at jeeves.server.JeevesEngine.init(JeevesEngine.java:191)
	at jeeves.server.sources.http.JeevesServlet.init(JeevesServlet.java:84)
	at javax.servlet.GenericServlet.init(GenericServlet.java:158)
	at org.eclipse.jetty.servlet.ServletHolder.initServlet(ServletHolder.java:492)
	at org.eclipse.jetty.servlet.ServletHolder.doStart(ServletHolder.java:312)
	at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:59)
	at org.eclipse.jetty.servlet.ServletHandler.initialize(ServletHandler.java:778)
	at org.eclipse.jetty.servlet.ServletContextHandler.startContext(ServletContextHandler.java:258)
	at org.eclipse.jetty.webapp.WebAppContext.startContext(WebAppContext.java:1221)
	at org.eclipse.jetty.server.handler.ContextHandler.doStart(ContextHandler.java:699)
	at org.eclipse.jetty.webapp.WebAppContext.doStart(WebAppContext.java:454)
	at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:59)
	at org.eclipse.jetty.deploy.WebAppDeployer.scan(WebAppDeployer.java:309)
	at org.eclipse.jetty.deploy.WebAppDeployer.doStart(WebAppDeployer.java:189)
	at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:59)
	at org.eclipse.jetty.util.component.AggregateLifeCycle.doStart(AggregateLifeCycle.java:63)
	at org.eclipse.jetty.server.handler.AbstractHandler.doStart(AbstractHandler.java:53)
	at org.eclipse.jetty.server.handler.HandlerWrapper.doStart(HandlerWrapper.java:91)
	at org.eclipse.jetty.server.Server.doStart(Server.java:262)
	at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:59)
	at org.eclipse.jetty.xml.XmlConfiguration$1.run(XmlConfiguration.java:1215)
	at java.security.AccessController.doPrivileged(Native Method)
	at org.eclipse.jetty.xml.XmlConfiguration.main(XmlConfiguration.java:1138)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.eclipse.jetty.start.Main.invokeMain(Main.java:457)
	at org.eclipse.jetty.start.Main.start(Main.java:602)
	at org.eclipse.jetty.start.Main.main(Main.java:82)
Caused by: java.nio.file.NoSuchFileException: /data_nfs/geonetwork_data/index/taxonomy/_7u.si
	at sun.nio.fs.UnixException.translateToIOException(UnixException.java:86)
	at sun.nio.fs.UnixException.rethrowAsIOException(UnixException.java:102)
	at sun.nio.fs.UnixException.rethrowAsIOException(UnixException.java:107)
	at sun.nio.fs.UnixFileSystemProvider.newFileChannel(UnixFileSystemProvider.java:177)
	at java.nio.channels.FileChannel.open(FileChannel.java:287)
	at java.nio.channels.FileChannel.open(FileChannel.java:335)
	at org.apache.lucene.store.MMapDirectory.openInput(MMapDirectory.java:196)
	at org.apache.lucene.store.NRTCachingDirectory.openInput(NRTCachingDirectory.java:232)
	at org.apache.lucene.store.Directory.openChecksumInput(Directory.java:113)
	at org.apache.lucene.codecs.lucene46.Lucene46SegmentInfoReader.read(Lucene46SegmentInfoReader.java:49)
	at org.apache.lucene.index.SegmentInfos.read(SegmentInfos.java:361)
	at org.apache.lucene.index.SegmentInfos$1.doBody(SegmentInfos.java:457)
	at org.apache.lucene.index.SegmentInfos$FindSegmentsFile.run(SegmentInfos.java:907)
	at org.apache.lucene.index.SegmentInfos$FindSegmentsFile.run(SegmentInfos.java:753)
	at org.apache.lucene.index.SegmentInfos.read(SegmentInfos.java:453)
	at org.apache.lucene.index.IndexWriter.<init>(IndexWriter.java:763)
	at org.apache.lucene.facet.taxonomy.directory.DirectoryTaxonomyWriter.openIndexWriter(DirectoryTaxonomyWriter.java:265)
	at org.apache.lucene.facet.taxonomy.directory.DirectoryTaxonomyWriter.<init>(DirectoryTaxonomyWriter.java:192)
	at org.apache.lucene.facet.taxonomy.directory.DirectoryTaxonomyWriter.<init>(DirectoryTaxonomyWriter.java:315)
	at org.apache.lucene.facet.taxonomy.directory.DirectoryTaxonomyWriter.<init>(DirectoryTaxonomyWriter.java:332)
	at org.fao.geonet.kernel.search.index.TaxonomyIndexTracker.init(TaxonomyIndexTracker.java:69)
	at org.fao.geonet.kernel.search.index.TaxonomyIndexTracker.<init>(TaxonomyIndexTracker.java:63)
	at org.fao.geonet.kernel.search.index.LuceneIndexLanguageTracker.lazyInit(LuceneIndexLanguageTracker.java:115)
	... 37 more