Erro ORA-12528 connecting to AUXILIARY Instance - RMAN Duplicate Database

If your database is in nomount, listener will show status as BLOCKED and to connect to this NOMOUNT database from a remote server you need to add (UR=A) in remote tnsnames.ora file as on example below:

DBNEW =

  (DESCRIPTION =

    (ADDRESS = (COMMUNITY = SAP.WORLD)(PROTOCOL = TCP)(HOST = hostname)(PORT = 1521)(QUEUESIZE = 90))

    (CONNECT_DATA =

      (SERVER = DEDICATED)

      (SERVICE_NAME = DBNEW.WORLD) (UR=A)

    )

  )