Spark UI returns 500 in yarn-client mode

HTTP ERROR 500

Problem accessing /proxy/application_1411648907638_0281/stages/. Reason:

    Connection refused
Caused by:

java.net.ConnectException: Connection refused
	at java.net.PlainSocketImpl.socketConnect(Native Method)
	at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:339)
	at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:200)
	at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:182)
	at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
	at java.net.Socket.connect(Socket.java:579)
	at java.net.Socket.connect(Socket.java:528)
	at java.net.Socket.<init>(Socket.java:425)
	at java.net.Socket.<init>(Socket.java:280)
	at org.apache.commons.httpclient.protocol.DefaultProtocolSocketFactory.createSocket(DefaultProtocolSocketFactory.java:80)
	at org.apache.commons.httpclient.protocol.DefaultProtocolSocketFactory.createSocket(DefaultProtocolSocketFactory.java:122)
	at org.apache.commons.httpclient.HttpConnection.open(HttpConnection.java:707)
	at org.apache.commons.httpclient.HttpMethodDirector.executeWithRetry(HttpMethodDirector.java:387)
	at org.apache.commons.httpclient.HttpMethodDirector.executeMethod(HttpMethodDirector.java:171)
	at org.apache.commons.httpclient.HttpClient.executeMethod(HttpClient.java:397)
	at org.apache.commons.httpclient.HttpClient.executeMethod(HttpClient.java:346)
	at org.apache.hadoop.yarn.server.webproxy.WebAppProxyServlet.proxyLink(WebAppProxyServlet.java:185)
	at org.apache.hadoop.yarn.server.webproxy.WebAppProxyServlet.doGet(WebAppProxyServlet.java:336)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:707)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:820)
	at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:511)
	at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1221)
	at com.google.inject.servlet.FilterChainInvocation.doFilter(FilterChainInvocation.java:66)
	at com.sun.jersey.spi.container.servlet.ServletContainer.doFilter(ServletContainer.java:900)
	at com.sun.jersey.spi.container.servlet.ServletContainer.doFilter(ServletContainer.java:834)
	at com.sun.jersey.spi.container.servlet.ServletContainer.doFilter(ServletContainer.java:795)
	at com.google.inject.servlet.FilterDefinition.doFilter(FilterDefinition.java:163)
	at com.google.inject.servlet.FilterChainInvocation.doFilter(FilterChainInvocation.java:58)
	at com.google.inject.servlet.ManagedFilterPipeline.dispatch(ManagedFilterPipeline.java:118)
	at com.google.inject.servlet.GuiceFilter.doFilter(GuiceFilter.java:113)
	at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1212)
	at org.apache.hadoop.http.lib.StaticUserWebFilter$StaticUserFilter.doFilter(StaticUserWebFilter.java:109)
	at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1212)
	at org.apache.hadoop.http.HttpServer2$QuotingInputFilter.doFilter(HttpServer2.java:1183)
	at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1212)
	at org.apache.hadoop.http.NoCacheFilter.doFilter(NoCacheFilter.java:45)
	at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1212)
	at org.apache.hadoop.http.NoCacheFilter.doFilter(NoCacheFilter.java:45)
	at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1212)
	at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:399)
	at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
	at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182)
	at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:766)
	at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:450)
	at org.mortbay.jetty.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:230)
	at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
	at org.mortbay.jetty.Server.handle(Server.java:326)
	at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542)
	at org.mortbay.jetty.HttpConnection$RequestHandler.headerComplete(HttpConnection.java:928)
	at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:549)
	at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:212)
	at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404)
	at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:410)
	at org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:582)
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