If you are redefining a table that has a materialized view log, then be careful to use the MView Log table name, rather than the MView Log name, for the registration
e.g.
-- Register MView Log: EXEC DBMS_REDEFINITION.REGISTER_DEPENDENT_OBJECT('SCOTT','SALES','SALES_INT',DBMS_REDEFINITION.CONS_MVLOG,'SCOTT','MLOG$_SALES','MLOG$_SALES_INT');