How do you troubleshoot "ClassNotFoundException" in a native image at runtime?

This almost always means the class was reachable only through reflection or a dynamic lookup that the build-time static analysis couldn't see, so it was stripped out of the final executable.

1. Re-run the application on a normal JVM under the native-image-agent: java -agentlib:native-image-agent=config-output-dir=META-INF/native-image -jar app.jar, exercising the exact code path that throws the exception.
2. Check the generated reflect-config.json to confirm the missing class and its constructors/methods got captured.
3. If the class is loaded by name from a string built at runtime (e.g. a plugin name from a config file), add it manually to the reflection config since the agent can only record paths it actually observes.
4. Rebuild with native-image and re-test the same code path.

If the class comes from a third-party library, check the GraalVM Reachability Metadata Repository first - there's a good chance someone has already published the correct configuration for that library and version.