Is there any reason for this exception? Which exactly server is shutting down if we use quorum of zookepers?

java.lang.IllegalStateException: Phoenix driver closed because server is shutting down at org.apache.phoenix.jdbc.PhoenixDriver.throwDriverClosedException(PhoenixDriver.java:290) at org.apache.phoenix.jdbc.PhoenixDriver.checkClosed(PhoenixDriver.java:285) at org.apache.phoenix.jdbc.PhoenixDriver.connect(PhoenixDriver.java:220) at java.sql.DriverManager.getConnection(DriverManager.java:664) at java.sql.DriverManager.getConnection(DriverManager.java:270)