I tried to restart HDFS, however, it always timeout at restarting namenode and HDFS will not be started. <small> java.net.ConnectException: sandbox.hortonworks.com:50070: Connection refused (Connection refused) at java.net.PlainSocketImpl.socketConnect(Native Method) at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:350) at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206) at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188) at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392) at java.net.Socket.connect(Socket.java:589) at sun.net.NetworkClient.doConnect(NetworkClient.java:175) at sun.net.www.http.HttpClient.openServer(HttpClient.java:432) at sun.net.www.http.HttpClient.openServer(HttpClient.java:527) at sun.net.www.http.HttpClient.<init>(HttpClient.java:211) at sun.net.www.http.HttpClient.New(HttpClient.java:308) at sun.net.www.http.HttpClient.New(HttpClient.java:326) at sun.net.www.protocol.http.HttpURLConnection.getNewHttpClient(HttpURLConnection.java:1202) at sun.net.www.protocol.http.HttpURLConnection.plainConnect0(HttpURLConnection.java:1138) at sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConnection.java:1032) at sun.net.www.protocol.http.HttpURLConnection.connect(HttpURLConnection.java:966) at org.apache.hadoop.hdfs.web.WebHdfsFileSystem$AbstractRunner.connect(WebHdfsFileSystem.java:710) at org.apache.hadoop.hdfs.web.WebHdfsFileSystem$AbstractRunner.connect(WebHdfsFileSystem.java:662) at org.apache.hadoop.hdfs.web.WebHdfsFileSystem$AbstractRunner.runWithRetry(WebHdfsFileSystem.java:735) at org.apache.hadoop.hdfs.web.WebHdfsFileSystem$AbstractRunner.access$100(WebHdfsFileSystem.java:582) at org.apache.hadoop.hdfs.web.WebHdfsFileSystem$AbstractRunner$1.run(WebHdfsFileSystem.java:612) at java.security.AccessController.doPrivileged(Native Method) at javax.security.auth.Subject.doAs(Subject.java:422) at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1724) at org.apache.hadoop.hdfs.web.WebHdfsFileSystem$AbstractRunner.run(WebHdfsFileSystem.java:608) at org.apache.hadoop.hdfs.web.WebHdfsFileSystem.listStatus(WebHdfsFileSystem.java:1484) at org.apache.ambari.view.utils.hdfs.HdfsApi$2.run(HdfsApi.java:110) at org.apache.ambari.view.utils.hdfs.HdfsApi$2.run(HdfsApi.java:108) at java.security.AccessController.doPrivileged(Native Method) at javax.security.auth.Subject.doAs(Subject.java:422) at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1724) at org.apache.ambari.view.utils.hdfs.HdfsApi.execute(HdfsApi.java:397) at org.apache.ambari.view.utils.hdfs.HdfsApi.listdir(HdfsApi.java:108) at org.apache.ambari.view.commons.hdfs.FileOperationService.listdir(FileOperationService.java:63) 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 com.sun.jersey.spi.container.JavaMethodInvokerFactory$1.invoke(JavaMethodInvokerFactory.java:60) at com.sun.jersey.server.impl.model.method.dispatch.AbstractResourceMethodDispatchProvider$ResponseOutInvoker._dispatch(AbstractResourceMethodDispatchProvider.java:205) at com.sun.jersey.server.impl.model.method.dispatch.ResourceJavaMethodDispatcher.dispatch(ResourceJavaMethodDispatcher.java:75) at com.sun.jersey.server.impl.uri.rules.HttpMethodRule.accept(HttpMethodRule.java:302) at com.sun.jersey.server.impl.uri.rules.RightHandPathRule.accept(RightHandPathRule.java:147) at com.sun.jersey.server.impl.uri.rules.SubLocatorRule.accept(SubLocatorRule.java:137) at com.sun.jersey.server.impl.uri.rules.RightHandPathRule.accept(RightHandPathRule.java:147) at com.sun.jersey.server.impl.uri.rules.SubLocatorRule.accept(SubLocatorRule.java:137) at com.sun.jersey.server.impl.uri.rules.RightHandPathRule.accept(RightHandPathRule.java:147) at com.sun.jersey.server.impl.uri.rules.SubLocatorRule.accept(SubLocatorRule.java:137) at com.sun.jersey.server.impl.uri.rules.RightHandPathRule.accept(RightHandPathRule.java:147) at com.sun.jersey.server.impl.uri.rules.SubLocatorRule.accept(SubLocatorRule.java:137) at com.sun.jersey.server.impl.uri.rules.RightHandPathRule.accept(RightHandPathRule.java:147) at com.sun.jersey.server.impl.uri.rules.SubLocatorRule.accept(SubLocatorRule.java:137) at com.sun.jersey.server.impl.uri.rules.RightHandPathRule.accept(RightHandPathRule.java:147) at com.sun.jersey.server.impl.uri.rules.ResourceClassRule.accept(ResourceClassRule.java:108) at com.sun.jersey.server.impl.uri.rules.RightHandPathRule.accept(RightHandPathRule.java:147) at com.sun.jersey.server.impl.uri.rules.RootResourceClassesRule.accept(RootResourceClassesRule.java:84) at com.sun.jersey.server.impl.application.WebApplicationImpl._handleRequest(WebApplicationImpl.java:1542) at com.sun.jersey.server.impl.application.WebApplicationImpl._handleRequest(WebApplicationImpl.java:1473) at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:1419) at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:1409) at com.sun.jersey.spi.container.servlet.WebComponent.service(WebComponent.java:409) at com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:558) at com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:733) at javax.servlet.http.HttpServlet.service(HttpServlet.java:848) at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:684) at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1507) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330) at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:118) at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:84) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.apache.ambari.server.security.authorization.AmbariAuthorizationFilter.doFilter(AmbariAuthorizationFilter.java:257) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:113) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:103) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:113) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:54) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:45) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.apache.ambari.server.security.authorization.jwt.JwtAuthenticationFilter.doFilter(JwtAuthenticationFilter.java:96) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.springframework.security.web.authentication.www.BasicAuthenticationFilter.doFilter(BasicAuthenticationFilter.java:150) at org.apache.ambari.server.security.authentication.AmbariAuthenticationFilter.doFilter(AmbariAuthenticationFilter.java:88) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.apache.ambari.server.security.authorization.AmbariUserAuthorizationFilter.doFilter(AmbariUserAuthorizationFilter.java:91) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:87) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:192) at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:160) at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:237) at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:167) at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1478) at org.apache.ambari.server.api.MethodOverrideFilter.doFilter(MethodOverrideFilter.java:72) at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1478) at org.apache.ambari.server.api.AmbariPersistFilter.doFilter(AmbariPersistFilter.java:47) at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1478) at org.apache.ambari.server.view.AmbariViewsMDCLoggingFilter.doFilter(AmbariViewsMDCLoggingFilter.java:54) at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1478) at org.apache.ambari.server.view.ViewThrottleFilter.doFilter(ViewThrottleFilter.java:161) at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1478) at org.apache.ambari.server.security.AbstractSecurityHeaderFilter.doFilter(AbstractSecurityHeaderFilter.java:109) at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1478) at org.apache.ambari.server.security.AbstractSecurityHeaderFilter.doFilter(AbstractSecurityHeaderFilter.java:109) at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1478) at org.eclipse.jetty.servlets.UserAgentFilter.doFilter(UserAgentFilter.java:82) at org.eclipse.jetty.servlets.GzipFilter.doFilter(GzipFilter.java:294) at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1478) at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:499) at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:137) at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:557) at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:231) at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1086) at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:427) at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:193) at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1020) at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:135) at org.apache.ambari.server.controller.AmbariHandlerList.processHandlers(AmbariHandlerList.java:212) at org.apache.ambari.server.controller.AmbariHandlerList.processHandlers(AmbariHandlerList.java:201) at org.apache.ambari.server.controller.AmbariHandlerList.handle(AmbariHandlerList.java:150) at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:116) at org.eclipse.jetty.server.Server.handle(Server.java:370) at org.eclipse.jetty.server.AbstractHttpConnection.handleRequest(AbstractHttpConnection.java:494) at org.eclipse.jetty.server.AbstractHttpConnection.headerComplete(AbstractHttpConnection.java:973) at org.eclipse.jetty.server.AbstractHttpConnection$RequestHandler.headerComplete(AbstractHttpConnection.java:1035) at org.eclipse.jetty.http.HttpParser.parseNext(HttpParser.java:641) at org.eclipse.jetty.http.HttpParser.parseAvailable(HttpParser.java:231) at org.eclipse.jetty.server.AsyncHttpConnection.handle(AsyncHttpConnection.java:82) at org.eclipse.jetty.io.nio.SelectChannelEndPoint.handle(SelectChannelEndPoint.java:696) at org.eclipse.jetty.io.nio.SelectChannelEndPoint$1.run(SelectChannelEndPoint.java:53) at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:608) at org.eclipse.jetty.util.thread.QueuedThreadPool$3.run(QueuedThreadPool.java:543) at java.lang.Thread.run(Thread.java:745)</small> ... View more