I don't know if this is worthy of a bug report, but yesterday I made
the mistake of trying to start the registry with:

        rmiregistry -Djava.security.policy=/my/file/policy

(rather than what I should have run:
        rmiregistry -J-Djava.security.policy=/my/file/policy)
                    ^^
and what I got was:

        Port is not a number.

Because I didn't know what I did wrong, I ran:

        rmiregistry -help

and what I got was:

        Port is not a number.

After several minutes of crying, I figured out what I did wrong, but
I thought perhaps a more detailed error message like "Setting a property
on a registry from the command line is not supported unless it is passed
in conjuntion with the "-J" option".

my $.02,
:)
jen