HTTP 500 Error for SparkUI in YARN Cluster mode

[Benyi Wang]

I got this error when I click "Track URL: ApplicationMaster" when I run a
spark job in YARN cluster mode. I found this jira
https://issues.apache.org/jira/browse/YARN-800, but I could not get this
problem fixed. I'm running CDH 5.1.0 with Both HDFS and RM HA enabled. Does
anybody has the similar issue? How do you fix this?HTTP ERROR 500

Problem accessing /proxy/application_1418016558670_0193/. 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)