ModuleNotFoundException: Missing Module on Module Path in Java 17

Quick Answer

The correct exception here is java.lang.module.FindException, because that is the specific exception the Java module system throws when module resolution, which runs before your application code ever executes, cannot locate a required module on the module path. ModuleNotFoundException sounds plausible because its name mirrors ClassNotFoundException, but it simply does not exist as a standard Java exception type, which is why questions like this test whether you actually know the API rather than guessing from naming conventions. The remaining distractors fail for a different reason: they are real exceptions, just not ones tied to this startup-time module resolution step. ExceptionInInitializerError is thrown later, when a class's static initializer fails, while NoClassDefFoundError and ClassNotFoundException both relate to ordinary class loading rather than to the module system verifying that every required module is present before the JVM even begins running your code. The pattern to remember is that missing-module problems surface as FindException during resolution, while missing-class problems surface as NoClassDefFoundError or ClassNotFoundException during class loading, since these are two separate phases of startup with two separate exception families. When a question describes a module missing from the module path, go straight to FindException rather than reaching for an exception name that merely sounds consistent with how Java normally names its 'not found' errors.