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

Message
java.nio.file.NoSuchFileException: /data/index/taxonomy/_u.si
Handler
org.fao.geonet.Geonetwork
Exception
java.lang.RuntimeException: java.nio.file.NoSuchFileException: /data/index/taxonomy/_u.si
Stack
java.lang.RuntimeException: java.nio.file.NoSuchFileException: /data/index/taxonomy/_u.si
	at org.fao.geonet.kernel.search.index.LuceneIndexLanguageTracker.lazyInit(LuceneIndexLanguageTracker.java:107)
	at org.fao.geonet.kernel.search.index.LuceneIndexLanguageTracker.acquire(LuceneIndexLanguageTracker.java:196)
	at org.fao.geonet.kernel.search.SearchManager.getIndexReader(SearchManager.java:1407)
	at org.fao.geonet.kernel.search.SearchManager.getNewIndexReader(SearchManager.java:1411)
	at org.fao.geonet.kernel.search.SearchManager.getDocsChangeDate(SearchManager.java:1066)
	at org.fao.geonet.kernel.DataManager.init(DataManager.java:238)
	at org.fao.geonet.Geonetwork.start(Geonetwork.java:380)
	at jeeves.server.JeevesEngine.initAppHandler(JeevesEngine.java:454)
	at jeeves.server.JeevesEngine.init(JeevesEngine.java:175)
	at jeeves.server.sources.http.JeevesServlet.init(JeevesServlet.java:82)
	at javax.servlet.GenericServlet.init(GenericServlet.java:158)
	at org.apache.catalina.core.StandardWrapper.initServlet(StandardWrapper.java:1230)
	at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1174)
	at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:1066)
	at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:5377)
	at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5669)
	at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
	at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:899)
	at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:875)
	at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:652)
	at org.apache.catalina.startup.HostConfig.deployWAR(HostConfig.java:1092)
	at org.apache.catalina.startup.HostConfig$DeployWar.run(HostConfig.java:1984)
	at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at java.lang.Thread.run(Thread.java:748)
Caused by: java.nio.file.NoSuchFileException: /data/index/taxonomy/_u.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:98)
	... 26 more