ERROR QueryResource:130 - Exception handling request: {class=io.druid.server.QueryResource, exceptio

Hi
While executing concurrent api group by queries in druid I am getting this below exception in druid broker.

ERROR QueryResource:130 - Exception handling request: {class=io.druid.server.QueryResource, exceptionType=class io.druid.java.util.common.RE, exceptionMessage=Failure getting results for query

I am not able to find out what causing this issue. Any one can explain me what causing this issue?