Mule - DataMapper throws "Error while validating DB connection."

Question

...org.jetel.connection.jdbc.DBConnection: Error while validating DB connection.
java.lang.NullPointerException
    at org.jetel.connection.jdbc.DBConnection.isValid(DBConnection.java:531)
    at org.jetel.connection.jdbc.DBConnection.getConnection(DBConnection.java:473)
    at org.jetel.lookup.DBLookupTable.preExecute(DBLookupTable.java:188)
    at org.jetel.graph.TransformationGraph.preExecute(TransformationGraph.java:526)
    at com.mulesoft.mule.module.datamapper...

Above is the error that I'm seeing in my MuleStudio console; however, according to datamapper DB lookup validation function (see image below), the DB connection seems fine.

Question: what is causing this error & how to fix this error?

Answer 1

It looks like the new Anypoint Studio does not have this issue.