How can I resolve this error - cannot create poolableconnectionfactory?

Cannot create poolableconnectionfactory means that JDBC Driver used by JMeter to establish connection with the database fails to communicate over the existing connection.

The reasons could be in: Version mismatch of the JDBC driver and the database, double check it and update/downgrade your JDBC driver

You are leaving connections open for a long amount of time hence database is running out of the available connections in the pool. Either increase open connections limit on the database side or ensure that connections are being closed at least on JMeter side. Your database server is overloaded therefore it cannot accept incoming connections anymore. Check database logs files for any suspicious entries. You can additionally ensure that it has enough headroom to operate using i.e. JMeter PerfMon Plugin And last but not the least, be aware that since JMeter 3.1 it is recommended to use JSR223 Test Elements and Groovy language so consider migrating your Beanshell test elements to JSR223 ones on the next available opportunity.