The mvc-krazo subsystem only exposes the MVC API and the krazo implementation to war deployments. This means if MVC components are packaged in libraries in an ear's lib directory, deployment will fail.

Of particular significance are the libraries provided by the https://github.com/eclipse-ee4j/krazo-extensions/tree/main project, which provide MVC ViewEngine implementations that integrate various frameworks that provide views. Packaging libraries like that in an ear/lib would be a reasonable thing to do if the ear include multiple wars that use MVC.