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

Message
java.lang.RuntimeException: org.apache.lucene.store.LockObtainFailedException: Lock obtain timed out: NativeFSLock@/var/lib/geonetwork_data/index/taxonomy/write.lock
Handler
org.fao.geonet.Geonetwork
Exception
java.lang.RuntimeException: java.lang.RuntimeException: org.apache.lucene.store.LockObtainFailedException: Lock obtain timed out: NativeFSLock@/var/lib/geonetwork_data/index/taxonomy/write.lock
Stack
java.lang.RuntimeException: java.lang.RuntimeException: org.apache.lucene.store.LockObtainFailedException: Lock obtain timed out: NativeFSLock@/var/lib/geonetwork_data/index/taxonomy/write.lock
	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:1202)
	at org.fao.geonet.kernel.search.SearchManager.getNewIndexReader(SearchManager.java:1207)
	at org.fao.geonet.kernel.search.SearchManager.getDocsChangeDate(SearchManager.java:890)
	at org.fao.geonet.kernel.datamanager.base.BaseMetadataManager.refreshIndex(BaseMetadataManager.java:251)
	at org.fao.geonet.kernel.datamanager.base.BaseMetadataManager$$FastClassBySpringCGLIB$$3a6cdaae.invoke(<generated>)
	at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204)
	at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:651)
	at org.fao.geonet.kernel.datamanager.draft.DraftMetadataManager$$EnhancerBySpringCGLIB$$4735ce76.refreshIndex(<generated>)
	at org.fao.geonet.kernel.DataManager.refreshIndex(DataManager.java:151)
	at org.fao.geonet.Geonetwork.start(Geonetwork.java:357)
	at org.fao.geonet.Geonetwork.start(Geonetwork.java:117)
	at jeeves.server.JeevesEngine.initAppHandler(JeevesEngine.java:457)
	at jeeves.server.JeevesEngine.init(JeevesEngine.java:193)
	at jeeves.server.sources.http.JeevesServlet.init(JeevesServlet.java:80)
	at javax.servlet.GenericServlet.init(GenericServlet.java:143)
	at org.apache.catalina.core.StandardWrapper.initServlet(StandardWrapper.java:1109)
	at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1061)
	at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:958)
	at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:4625)
	at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:4933)
	at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:171)
	at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:710)
	at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:687)
	at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:661)
	at org.apache.catalina.startup.HostConfig.deployDirectory(HostConfig.java:1177)
	at org.apache.catalina.startup.HostConfig$DeployDirectory.run(HostConfig.java:1925)
	at java.util.concurrent.Executors$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:750)
Caused by: java.lang.RuntimeException: org.apache.lucene.store.LockObtainFailedException: Lock obtain timed out: NativeFSLock@/var/lib/geonetwork_data/index/taxonomy/write.lock
	at org.fao.geonet.kernel.search.index.LuceneIndexLanguageTracker.lazyInit(LuceneIndexLanguageTracker.java:124)
	at org.fao.geonet.kernel.search.index.LuceneIndexLanguageTracker.close(LuceneIndexLanguageTracker.java:400)
	at org.fao.geonet.kernel.search.index.LuceneIndexLanguageTracker.close(LuceneIndexLanguageTracker.java:457)
	at org.fao.geonet.kernel.search.index.LuceneIndexLanguageTracker.init(LuceneIndexLanguageTracker.java:142)
	at org.fao.geonet.kernel.search.index.LuceneIndexLanguageTracker.lazyInit(LuceneIndexLanguageTracker.java:116)
	... 32 more
Caused by: org.apache.lucene.store.LockObtainFailedException: Lock obtain timed out: NativeFSLock@/var/lib/geonetwork_data/index/taxonomy/write.lock
	at org.apache.lucene.store.Lock.obtain(Lock.java:89)
	at org.apache.lucene.index.IndexWriter.<init>(IndexWriter.java:724)
	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)
	... 36 more