I had a similar problem, no error log. I'm adding this response for future me's, because it might help someone but unfortunately it's not a response to this exact question because I'm also a beginner and I don't know Websphere. (I was starting my server with JdkHttpServerFactory.createHttpServer()).

1. No error log:

By following the breakpoint I set in ContainerRequestFilter.filer(ContainerRequestContext) registered on my ResourceConfig class, I was able to determine that the error was thrown in:

org.glassfish.jersey.server.ServerRuntime.process(final ContainerRequest)

ContainerResponse response = endpoint.apply(data);

: "java.lang.UnsupportedOperationException: Method suspend is not supported by the container."

so I added an ExceptionLogger on my ResourceConfig, as in Jersey... how to log all exceptions, but still invoke ExceptionMappers. yay, now at least I have an error log.

2)

Then I switched to GrizzlyHttpServerFactory.createHttpServer instead of JdkHttpServerFactory.createHttpServer because I guess that's what was meant by "the container" -- yay, @Suspended worked.