https://community.cloudera.com/t5/Support-Questions/Null-Pointer-Exception-in-ambari-server-logs-after-ambari/m-p/230534#M192384 <P><A rel="user" href="https://community.cloudera.com/users/17123/rafaelgomezg.html" nodeid="17123">@Rafael Gomez</A></P><P>The issue that you are afcing indicates Ambari DB Corruption. As we see that /request URL itslef is throwing NullPointerException so it will not be able to process any further request.</P><PRE>15 May 2017 07:16:14,016 WARN [qtp-ambari-client-26] ServletHandler:563 - /api/v1/clusters/hadoop/requests java.lang.NullPointerException</PRE><P>.</P><P>If you started noticing this issue happening after installing HUE service then please delete the HUE service from ambari Database completely by running the following queries on Ambari DB and then restart ambari server to see if it fixes your issue. </P><PRE> delete from hostcomponentstate where service_name = 'HUE'; delete from hostcomponentdesiredstate where service_name = 'HUE'; delete from servicecomponentdesiredstate where service_name = 'HUE'; delete from servicedesiredstate where service_name = 'HUE'; delete from serviceconfighosts where service_config_id in (select service_config_id from serviceconfig where service_name = 'HUE'); delete from serviceconfigmapping where service_config_id in (select service_config_id from serviceconfig where service_name = 'HUE'); delete from serviceconfig where service_name = 'HUE'; delete from requestresourcefilter where service_name = 'HUE'; delete from requestoperationlevel where service_name = 'HUE'; delete from clusterservices where service_name ='HUE'; delete from clusterconfig where type_name like 'hue%'; delete from clusterconfigmapping where type_name like 'hue%';</PRE><P>.</P><P><STRONG>NOTE: Please take a Ambari Database Dump before manipulating the Ambari DB.</STRONG></P> Tue, 16 May 2017 22:47:54 GMT jsensharma 2017-05-16T22:47:54Z