Meaning of error msg

What does the following error mean?
I am trying to use external authentication!

=ERROR REPORT==== 2006-03-27 12:53:05 ===
** State machine <0.377.0> terminating 
** Last event in was {xmlstreamelement,
                         {xmlelement,"auth",
                                     [{"mechanism","PLAIN"},
                                      {"xmlns",
                                       "urn:ietf:params:xml:ns:xmpp-sasl"}],
                                     [{xmlcdata,
                                          "NjAwQHNwcmFkZWVwADYwMABkZWVweg=="}]}}
** When State == wait_for_feature_request
**      Data  == {state,#Port<0.371>,
                        <0.378.0>,
                        gen_tcp,
                        "190105064",
                        {sasl_state,"jabber",
                                    "spradeep",
                                    [],
                                    #Fun<ejabberd_c2s.1.99667652>,
                                    #Fun<ejabberd_c2s.2.115961139>,
                                    undefined,
                                    undefined},
                        c2s,
                        c2s_shaper,
                        false,
                        false,
                        false,
                        [],
                        false,
                        undefined,
                        [],
                        "spradeep",
                        [],
                        {0,nil},
                        {0,nil},
                        {0,nil},
                        {0,nil},
                        undefined,
                        undefined,
                        undefined,
                        false,
                        none,
                        "en"}
** Reason for termination = 
** {badarg,[{extauth,call_port,2},
            {cyrsasl_plain,mech_step,2},
            {cyrsasl,server_step,2},
            {ejabberd_c2s,wait_for_feature_request,2},
            {gen_fsm,handle_msg,7},
            {proc_lib,init_p,5}]}