I don't know if the "could not find or load main class" error is even related to kotlin. I used jar -tf to list classes, and the class I set as main was right. I unzipped the jar, and I could see that the class was there and the fq name matched. There may just be an issue with my JDK. Sometimes when I specify the main class (exact same as is in the Manifest file) explicitly, it will run, but then hits random native errors that I don't see when running in intellij.