ORA-23357: the propagator does not exist tips

Question: I'm trying to define a propagator for a materialized view and I'm getting the "ORA-23357: the propagator does not exist" error:

How do I check the status of materialized view propagators?

Answer:  Please see Col. Garmany's notes on defining a replication propagator for a materialized view, especially the part about the repadmin user.  Also see these notes on creating materialized view refresh groups.

The docs note this on the ORA-23357 error, a generic note that the propagator is missing:

ORA-23357: the propagator does not exist

Cause: The propagator does not exist.

Action: Register a new propagator.

On the remote site, replication is administered by repadmin. Repadmin is the snapshot administrator, the propagator, and the refresher. A database link connects repadmin with repproxy. Using a private link restricts user access to the base tables on the master site. Repproxy is granted rights to the objects being replicated. Repadmin (on the remote site) contacts repproxy and pushes changes, which repproxy applies. Oracle provides these views for monitoring replication:

DBA_REPSCHEMA. This view contains details for the replication schema.

DBA_REPCATLOG. This view provides a log of all replication activities.

DBA_JOBS. Use this view to monitor all scheduled job in the database.

DBA_REPCAT. This view shows the replication catalog.

ALL_REPCONFLICT. This view provides a list of all replication conflicts.

ALL_REPRESOLUTION. For systems defined with pre-defined conflict resolution, this view lists the resolution of every conflict.

DBA_REPOBJECT. This view gives you a list of al replicated objects.

DBA_REPSITES. This view provides is a list of replicated sites.
 

Also, these scripts check the staus of replication:

connect repadmin/repadmin

set pages 50000

col sname      format a20 head "SchemaName"
col masterdef  format a10 head "MasterDef?"
col oname      format a20 head "ObjectName"
col gname      format a20 head "GroupName"
col object     format a35 trunc
col dblink     format a35 head "DBLink"
col message    format a25
col broken     format a6 head "Broken?"

prompt Replication schemas/ sites
select 
  sname, 
  masterdef, 
  dblink
from
  sys.dba_repschema;

prompt RepCat Log (after a while you should see no entries):
select 
   request, 
   status, 
   message, 
   errnum
from
   sys.dba_repcatlog;

prompt Entries in the job queue
select 
   job, 
   last_date, 
   last_sec, 
   next_date, 
   next_sec, 
   broken, 
   failures,
   what
from
   sys.dba_jobs
where
   schema_user = 'REPADMIN';

prompt Replication Status:
select 
   sname, 
   master, 
   status
from
   sys.dba_repcat;

prompt Returns all conflict resolution methods
select * from all_repconflict;

prompt Returns all resolution methods in use
select * from all_represolution;

prompt Objects registered for replication
select 
   gname, 
   type||' '||sname||'.'||oname object, 
   status
from
   sys.dba_repobject;

select * from dba_repsites;