Исключение java.lang.NoClassDefFoundError в org/apache/logging/log4j/LogManager

Подскажите, в чем причина исключения

Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/logging/log4j/LogManager
        at ru.sfedu.SchoolMeals.SchoolClient.<clinit>(SchoolClient.java:14)
Caused by: java.lang.ClassNotFoundException: org.apache.logging.log4j.LogManager
        at java.net.URLClassLoader.findClass(Unknown Source)
        at java.lang.ClassLoader.loadClass(Unknown Source)
        at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
        at java.lang.ClassLoader.loadClass(Unknown Source)

Код:

public class SchoolClient {
    private static Logger log = LogManager.getLogger(SchoolClient.class);

    public SchoolClient(){
        log.debug("<ConstructorName>[0]: starting application.........");
    }

    public static void main(String[] args) throws IOException {
        new SchoolClient();
        logBasicSystemInfo();
    }
    public static void logBasicSystemInfo() throws IOException {
        log.info("Launching the application...");
        ...
    }