java.sql.SQLException：未知的系统变量'transaction_isolation'

Question

I manually changed the version of mysql from 5.6.51 to 8.0.28, Then I used my java program to connect mysql and got the following error

java.sql.SQLException: Unknown system variable 'transaction_isolation'
at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:129)
at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:122)
at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:829)
at com.mysql.cj.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:449)
at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:242)
at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:198)
at java.sql.DriverManager.getConnection(DriverManager.java:664)
at java.sql.DriverManager.getConnection(DriverManager.java:247)

Below is my mysql Connector/J version

<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>8.0.28</version>
</dependency>

Answer 1

I may have found the reason, the reason is that I only modified the version number on the surface, but in fact java calls 'transaction_isolation' of mysql v8 according to the version information, and my mysql is actually only v5, missing 'transaction_isolation'