ClassNotFoundException: com.mysql.cj.jdbc.Driver

This error occurs when the JVM (Java Virtual Machine) is unable to locate the MySQL JDBC driver in the classpath.

To resolve this issue, follow these steps:

1. Make sure that the MySQL JDBC driver is added to the classpath of your project. You can download the driver from the official MySQL website.

2. Check that the class name is correct. In older versions of the MySQL JDBC driver, the class name was "com.mysql.jdbc.Driver". However, in newer versions, the class name has changed to "com.mysql.cj.jdbc.Driver".

3. If you are using an IDE like Eclipse or IntelliJ, make sure that the MySQL JDBC driver is included in the project's build path.

4. Restart your application or server.

If the above steps do not resolve the issue, you may need to check if the MySQL server is running and make sure that the connection details (URL, username, and password) are correct in the application's code.