n thread "main" java.lang.ClassNotFoundException: com.mysql.jdbc.Driver

This error occurs when the Java Virtual Machine (JVM) is unable to find the required JDBC driver for connecting to a MySQL database. Here are some possible solutions to fix this error:

1. Check if the MySQL JDBC driver JAR file is included in the classpath of your Java project. You can download the latest version of the driver from the official MySQL website and add it to your project's build path.

2. Check if the class name for the JDBC driver is spelled correctly. The correct class name for MySQL JDBC driver is "com.mysql.cj.jdbc.Driver".

3. Check if the JDBC URL for connecting to the MySQL database is correct. It should be in the format "jdbc:mysql://hostname:port/databaseName".

4. Check if the MySQL server is running and accessible from your Java application. You can test the connection using a MySQL client tool like MySQL Workbench.

5. If you are using an IDE like Eclipse or IntelliJ IDEA, try refreshing the project or rebuilding it to ensure that all dependencies are properly resolved.

6. If none of the above solutions work, try restarting your computer or IDE as sometimes the JVM can get stuck and fail to load the driver.