The message "Warning Message: You cannot play/edit this mission; it is dependent on downloadable content that has been deleted.
a3_characters_f" is just a false warning that doesn't prevent the server from starting up or missions to be loaded.

I also have:

In arma3server.cfg:

Server crashes 100% of the time instantly at startup.

I also had segfaults when starting dedicated server on Ubuntu 16.04.3 LTS until removing the "-netlog" flag. That seemed to do the trick..