New Mysql Driver Causes Java. Sql. Sqlnontransientconnectionexception: Client_Plugin_Auth Is Required

This sounds like a regression. Was there a particular reason to switch to 6.0.2? If not, I'd revert back to 5.1.38 and give 6.x a shot after three months to let folks at MySQL to stabilize the driver.

It seems new versions of mysql connector (from 6 on) are not compatible with old version of the DBMS mysql(below 5.6). So in order to solve your problem, if you make an update of mysql connector, try to do the same with the DBMS. Actually I had the same issu with mysql connector 8.0.13 and the DBMS msql 5.1.... I solved it by moving the DBMS to 5.6.17

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

<parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.1.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

to

<parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.0.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    Use Maven depandency 
###pom.xml  
           <dependency>
                <groupId>mysql</groupId>
                <artifactId>mysql-connector-java</artifactId>
                <version>5.1.37</version>
            </dependency>

##application.properties

server.port=9092
jwt.secret=javainuse
spring.datasource.url=jdbc:mysql://localhost:3306/hospital
spring.datasource.username=root
spring.datasource.password=root
spring.datasource.driver-class-name= com.mysql.jdbc.Driver
spring.datasource.platform=mysql
#spring.jpa.hibernate.ddl-auto=create-drop

spring.jpa.properties.hibernate.dialect= org.hibernate.dialect.MySQL5InnoDBDialect
spring.jpa.hibernate.ddl-auto= update

#spring.jpa.properties.hibernate.dialect= org.hibernate.dialect.MySQL5InnoDBDialect

It may be due to mysql version is too old so you need to do 3 changes in that case: in application.properties do first 2 changes:

1. spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.MySQL5Dialect

2. spring.datasource.driver-class-name=com.mysql.jdbc.Driver

3. Do changes in pom.xml file in dependency of mysql-connector-java replace scope tag to the version tag and in version write your mysql version like 5.1

I resolve this problem by removing mysql version in pom.

<dependency>
     <groupId>mysql</groupId>
     <artifactId>mysql-connector-java</artifactId>       
</dependency>