Error RDFXX

.....: Empty string is not a valid argument to iri_to_id (), type 182
in
iri_to_id:(BIF),
        __01 => '',
FCT.DBA.check_auth_and_acls:211,
   serviceId => NULL,
  auth_method => 0,
       graph => '',
  parentPage => 'https://geosparql.demo.openlinksw.com/fct/rdfdesc/settings.vsp?g=',
  sponge_request => 0,
WS.WS./DAV/VAD/fct/rdfdesc/settings.vsp:44,
        path => (ARRAY_OF_POINTER value, tag 193),
      params => (ARRAY_OF_POINTER value, tag 193),
       lines => (ARRAY_OF_POINTER value, tag 193),
signal:(BIF),
        __01 => 'RDFXX',
        __02 => '.....: Empty string is not a valid argument to iri_to_id (), type 182
in
iri_to_id:(BIF),
        __' (truncated),
WS.WS.GET([executable]/dav.sql:2948),
        path => (ARRAY_OF_POINTER value, tag 193),
      params => (ARRAY_OF_POINTER value, tag 193),
       lines => (ARRAY_OF_POINTER value, tag 193)