我有一个一主一从的集群。我的群集工作正常，突然出现以下错误，导致我的资源管理器ui无法加载：

HTTP ERROR 500

Problem accessing /cluster. Reason:

    INTERNAL_SERVER_ERROR
Caused by:

java.lang.NullPointerException
    at org.apache.http.client.utils.URLEncodedUtils.parse(URLEncodedUtils.java:235)
    at org.apache.hadoop.security.token.delegation.web.ServletUtils.getParameter(ServletUtils.java:48)
    at org.apache.hadoop.security.token.delegation.web.DelegationTokenAuthenticationHandler.managementOperation(DelegationTokenAuthenticationHandler.java:170)
    at org.apache.hadoop.security.authentication.server.AuthenticationFilter.doFilter(AuthenticationFilter.java:502)
    at org.apache.hadoop.yarn.server.security.http.RMAuthenticationFilter.doFilter(RMAuthenticationFilter.java:84)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1212)
    at org.apache.hadoop.http.HttpServer2$QuotingInputFilter.doFilter(HttpServer2.java:1224)
    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)

如果我尝试检查正在运行的守护程序，我可以看到rm守护程序正在按照以下方式运行：

[hadoop@cluster-test hadoop]$ jps
22263 Jps
21549 NameNode
21888 ResourceManager
21733 SecondaryNameNode

我的rm日志中也有以下错误日志，但这些错误不会经常出现。我不确定这些问题是否相关。我想在这里分享一下，因为这可能会有助于了解以下问题的人：

2016-07-05 17:41:49,878 ERROR   org.apache.hadoop.yarn.server.resourcemanager.ResourceManager: RECEIVED SIGNAL   15: SIGTERM
2016-07-05 17:41:49,884 ERROR  org.apache.hadoop.security.token.delegation.AbstractDelegationTokenSecretManager : ExpiredTokenRemover received java.lang.InterruptedException: sleep interrupted

我正在使用以下hadoop版本：

Hadoop 2.6.0
Subversion https://git-wip-us.apache.org/repos/asf/hadoop.git -r    e3496499ecb8d220fba99dc5ed4c99c8f9e33bb1
Compiled by jenkins on 2014-11-13T21:10Z
Compiled with protoc 2.5.0

请帮助我，因为我已经坚持了很长一段时间，不能从谷歌得到太多的帮助。
非常感谢您的帮助！