We have seen issues with some clients failing to communicate with qserv after upgrade to mariadb 10.2.14. Two notable cases are JDBC (see
DM-14924) and nagios test script which is Perl script using DBI.
JDBC workaround was to downgrade to older version of JDBC. I think usePipelineAuth connection attribute is a suspect but I remember Kenny was playing with in recent JDBC is and it did not help much, so there may be other reason for it.
Nagios script has trouble on Ubuntu but works fine on CentOS7, I think the difference is due to older version of mysqlclient installed on CentOS7 (I had used system-installed Perl DBI).