Oracle to Postgres migration

Hi,

I have below query used in Oracle but while migrating to Postgres this code
is not supported in Postgres.
Could you please tell me how to resolve this?

SELECT p.id_po, p.line_number,
replace(replace(replace(RTRIM(XMLAGG(XMLELEMENT(name C,
regexp_replace(p.protocol_number,'([[:cntrl:]])','', 'g'))ORDER BY 1), ','
) ,'</C><C>','/'),'<C>',''),'</C>','') AS protocol_number

,replace(replace(replace(RTRIM(XMLAGG(XMLELEMENT(name C,
regexp_replace(p.protocol_status,'([[:cntrl:]])','', 'g'))ORDER BY 1), ','
) ,'</C><C>','/'),'<C>',''),'</C>','') AS protocol_status

,replace(replace(replace(RTRIM(XMLAGG(XMLELEMENT(name C,
regexp_replace(p.protocol_approver,'([[:cntrl:]])','', 'g'))ORDER BY 1),
',' ) ,'</C><C>','/'),'<C>',''),'</C>','') AS protocol_approver
,max(p.protocol_date) AS protocol_date

,replace(replace(replace(RTRIM(XMLAGG(XMLELEMENT(name C,
regexp_replace(p.protocol_nota,'([[:cntrl:]])','', 'g'))ORDER BY 1), ',' )
,'</C><C>','/'),'<C>',''),'</C>','') AS protocol_nota
,sum(coalesce(p.protocol_value,0)) protocol_value
FROM podl_extended_protocol p
where upper(p.protocol_status) not in
('REJEITADO','ELIMINADO')
group by p.id_po, p.line_number

Thanks,
Bimal