WAR file: Could not find or load main class, but it’s there

CBlew :

I have built a WAR archive artifact with Intellij IDEA that contains a Spring Boot MVC application written in Kotlin.

Here’s the relevant contents:

$ jar tvf application.war
...
1649 [timestamp] WEB-INF/classes/org/domain/apps/App00HelloMvcKt.class
2087 [timestamp] WEB-INF/classes/org/domain/apps/App00HelloMvc.class
...

App00HelloMvcKt contains fun main(...), and App00HelloMvc is the Spring Boot application class.

MANIFEST.MF contains Main-Class entry:

Main-Class: org.domain.apps.App00HelloMvcKt

However, when I run it, there is a problem:

$ java -jar application.war
Error: Could not find or load main class org.domain.apps.App00HelloMvcKt
Caused by: java.lang.ClassNotFoundException: org.domain.apps.App00HelloMvcKt

As I understand it, with this directory structure, no additional fumbling with class path is required. Then why is it unable to run?

---

Additional info: This is a teaching project. I am trying to serve .jsp pages from Spring Boot MVC application with embedded Tomcat. According to the internet, this setup only works if you package the app into a WAR and run it with java -jar.

Karol Dowbecki :

Most likely IntelliJ "Web Application: Archive" doesn't fully understand Spring Boot semantics. Try packaging the WAR with Maven Spring Boot Plugin, as in explained in chapter 68.2 Packaging Executable Jar and War Files:

$ mvn clean package spring-boot:repackage
$ java -jar target/application.war