https://community.cloudera.com/t5/Support-Questions/ZOOKEEPER-CHECK-FAILED/m-p/242435#M204236 <P><A rel="user" href="https://community.cloudera.com/users/113056/adilbakkourigi.html">@Adil BAKKOURI</A></P><P>Ambari Simply makes use of the Zookeeper Smoke Test "zkSmoke.sh" script to verify the Zookeeper Connection and if it can create &amp; delete the dummy ZNode "/zk_smoketest" inside the zookeeper host or not?</P><P>As you see the following message:</P><PRE>ExecutionFailed: Execution of '/var/lib/ambari-agent/tmp/zkSmoke.sh /usr/hdp/current/zookeeper-client/bin/zkCli.sh ambari-qa /usr/hdp/current/zookeeper-client/conf 2181 False kinit no_keytab no_principal /var/lib/ambari-agent/tmp/zkSmoke.out' returned 4. zk_node1=master.rh.bigdata.cluster&nbsp; . . Exception in thread "main" org.apache.zookeeper.KeeperException$ConnectionLossException: KeeperErrorCode = ConnectionLoss for /zk_smoketest &nbsp;</PRE><P><BR /></P><P>Which means your Zookeeper process might not be running file. Most probably the Zookeeper port might not be accessible on host <STRONG>"master.rh.bigdata.cluster"</STRONG></P><P>So you will need to first check if your Zookeeper is running fine or not on host "master.rh.bigdata.cluster" and if the Zookeeper port 2181 is listening fine or not?</P><PRE># ps -ef | grep -i zookeeper # netstat -tnlpa | grep 2181 # service iptables stop</PRE><P><BR /></P><P><STRONG>Most Possible Cause: </STRONG></P><P>If you see that Zookeeper process is not running then please try to restart it and check the Zookeper Logs to find any issue/ startup failure and please share the log.</P><P>Most probably once your Zookeeper is running fine and the port 2181 is accessible then your Zookeeper Check Should also run fine.</P><P>Firewall or Port Blocking issue:</P><P>So please go to the host where the SmokeTest is failing and then try to telnet to Zookeeper Host &amp; Port to see if that is accessible?</P><PRE># telnet <STRONG>master.rh.bigdata.cluster &nbsp;2181</STRONG> <STRONG>(OR)</STRONG> <STRONG># nc -v <STRONG>master.rh.bigdata.cluster &nbsp;2181</STRONG></STRONG></PRE><P><BR /></P><P><STRONG>Manual Test:</STRONG></P><P>You your self can try running the same command to verify this Zookeeper Zmoke Test run Try running this command on different Zookeeper nodes as it is.</P><PRE># /var/lib/ambari-agent/tmp/zkSmoke.sh /usr/hdp/current/zookeeper-client/bin/zkCli.sh ambari-qa /usr/hdp/current/zookeeper-client/conf 2181 False kinit no_keytab no_principal /var/lib/ambari-agent/tmp/zkSmoke.out</PRE><P><BR /></P><P>.</P><P>.</P><P><BR /></P> Fri, 14 Jun 2019 04:36:33 GMT jsensharma 2019-06-14T04:36:33Z