Cannot load JDBC driver class 'org.mysql.jdbc.Driver'

이런 오류가 나는데,

HTTP Status 500 – Internal Server Error
Type Exception Report

Message Request processing failed; nested exception is org.mybatis.spring.MyBatisSystemException: nested exception is org.apache.ibatis.exceptions.PersistenceException:

Description The server encountered an unexpected condition that prevented it from fulfilling the request.

Exception

org.springframework.web.util.NestedServletException: Request processing failed; nested exception is org.mybatis.spring.MyBatisSystemException: nested exception is org.apache.ibatis.exceptions.PersistenceException: 
### Error querying database.  Cause: org.springframework.jdbc.CannotGetJdbcConnectionException: Failed to obtain JDBC Connection; nested exception is org.apache.commons.dbcp.SQLNestedException: Cannot load JDBC driver class 'org.mysql.jdbc.Driver'
### The error may exist in org/example/repository/UserMapper.java (best guess)
### The error may involve org.example.repository.UserMapper.selectAll
### The error occurred while executing a query
### Cause: org.springframework.jdbc.CannotGetJdbcConnectionException: Failed to obtain JDBC Connection; nested exception is org.apache.commons.dbcp.SQLNestedException: Cannot load JDBC driver class 'org.mysql.jdbc.Driver'
    org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1014)
...[생략]...
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
Root Cause

org.mybatis.spring.MyBatisSystemException: nested exception is org.apache.ibatis.exceptions.PersistenceException: 
### Error querying database.  Cause: org.springframework.jdbc.CannotGetJdbcConnectionException: Failed to obtain JDBC Connection; nested exception is org.apache.commons.dbcp.SQLNestedException: Cannot load JDBC driver class 'org.mysql.jdbc.Driver'
### The error may exist in org/example/repository/UserMapper.java (best guess)
### The error may involve org.example.repository.UserMapper.selectAll
### The error occurred while executing a query
### Cause: org.springframework.jdbc.CannotGetJdbcConnectionException: Failed to obtain JDBC Connection; nested exception is org.apache.commons.dbcp.SQLNestedException: Cannot load JDBC driver class 'org.mysql.jdbc.Driver'
    org.mybatis.spring.MyBatisExceptionTranslator.translateExceptionIfPossible(MyBatisExceptionTranslator.java:75)
...[생략]...
    javax.servlet.http.HttpServlet.service(HttpServlet.java:733)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
Root Cause

org.apache.ibatis.exceptions.PersistenceException: 
### Error querying database.  Cause: org.springframework.jdbc.CannotGetJdbcConnectionException: Failed to obtain JDBC Connection; nested exception is org.apache.commons.dbcp.SQLNestedException: Cannot load JDBC driver class 'org.mysql.jdbc.Driver'
### The error may exist in org/example/repository/UserMapper.java (best guess)
### The error may involve org.example.repository.UserMapper.selectAll
### The error occurred while executing a query
### Cause: org.springframework.jdbc.CannotGetJdbcConnectionException: Failed to obtain JDBC Connection; nested exception is org.apache.commons.dbcp.SQLNestedException: Cannot load JDBC driver class 'org.mysql.jdbc.Driver'
    org.apache.ibatis.exceptions.ExceptionFactory.wrapException(ExceptionFactory.java:26)
...[생략]...
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
Root Cause

org.springframework.jdbc.CannotGetJdbcConnectionException: Failed to obtain JDBC Connection; nested exception is org.apache.commons.dbcp.SQLNestedException: Cannot load JDBC driver class 'org.mysql.jdbc.Driver'
    org.springframework.jdbc.datasource.DataSourceUtils.getConnection(DataSourceUtils.java:82)
...[생략]...
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
Root Cause

org.apache.commons.dbcp.SQLNestedException: Cannot load JDBC driver class 'org.mysql.jdbc.Driver'
    org.apache.commons.dbcp.BasicDataSource.createConnectionFactory(BasicDataSource.java:1429)
...[생략]...
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
Root Cause

java.lang.ClassNotFoundException: org.mysql.jdbc.Driver
    org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1372)
...[생략]...
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
Note The full stack trace of the root cause is available in the server logs.

<property name="driverClassName" value="org.mysql.jdbc.Driver" />

<property name="driverClassName" value="com.mysql.cj.jdbc.Driver" />