Please update the used MySQL Connector version from currently used 5.1.38 (release on 2015-12-07 ) (./plugins/com.mysql.jdbc_5.1.38.jar) to at least 5.1.46, but much better to active branch 8.0.15
Why is that update required?
I migrated my MySQL DB to latest 8.0.x and default password handling was changed.
This required the client to know that new caching_sha2_password
authentication plugin for MySQL 8.0.
https://dev.mysql.com/doc/relnotes/connector-j/5.1/en/news-5-1-46.html
But since the 5.1.x branch is not longer the active branch, please update directly to MySQL Connector 8.0.15
Security downgrade by adding DB user with mysql_native_password is no option
CREATE USER 'account'@'localhost' IDENTIFIED WITH mysql_native_password BY 'pass123';
After I removed the ./plugins/com.mysql.jdbc_5.1.38.jar from Katalon installation and placed the mysql-connector-java-8.0.15.jar there I’m able to connect to my DB again without getting
java.sql.SQLException: Unable to load authentication plugin 'caching_sha2_password'