If change MySQL JDBC driver from 5.1.38 to 6.0.2 I get the following exception
5.1.38
6.0.2
java.sql.SQLNonTransientConnectionException: CLIENT_PLUG
I had the same issue and I resolved by changing the parent tag version from 2.1.1.RELEASE to 2.0.0.RELEASE
from
org.springframework.boot spring-boot-starter-parent 2.1.1.RELEASE
to
org.springframework.boot spring-boot-starter-parent 2.0.0.RELEASE