Hello @amit_hadoop    Thanks for using Cloudera Community. Based on the Post, You installed HDP Sandbox 3.0 & observed Timeline Service v2 Reader reporting [1].    If you observe the Port mentioned, It says "17020" & HBase RegionServer runs with "16020" Port by default. YARN Timeline Service uses an Embedded HBase Service, which isn't equivalent to HBase Service as we may see in the Ambari UI. Kindly let us know the Outcome of the below Steps:   Whether Restarting YARN Timeline Service (Which restarts the Embedded HBase Service) helps, Within the YARN Logs, We should have an Embedded HBase Logs for HMaster & RegionServer. Reviewing the Logs may offer additional clue into the reasoning for Embedded HBase concerns, Review [2] for similar concerns wherein the ZNode was Cleared & Service Restarted, Review [3] for Documentation on Deleting the ZNode & Data. Restarting the YARN Timeline Service should initialise the HBase Setup afresh.    Regards, Smarak   [1] Error Trace: 2021-09-29 05:47:58,587 INFO [main] client.RpcRetryingCallerImpl: Call exception, tries=6, retries=36, started=5385 ms ago, cancelled=false, msg=org.apache.hadoop.hbase.ipc.ServerNotRunningYetException: Server sandbox-hdp.hortonworks.com,17020,1632894462010 is not running yet details=row 'prod.timelineservice.entity' on table 'hbase:meta' at region=hbase:meta,,1.1588230740, hostname=sandbox-hdp.hortonworks.com,17020,1628801419880, seqNum=-1 [2] https://community.cloudera.com/t5/Support-Questions/Yarn-Timeline-Service-V2-not-starting/td-p/281368 [3] https://docs.cloudera.com/HDPDocuments/HDP3/HDP-3.1.4/data-operating-system/content/remove_ats_hbase_before_switching_between_clusters.html     ... View more