RMAN-03002: failure of Duplicate Db command at 06/18/2021 18:58:07-RMAN-05501: aborting duplication of target database-RMAN-03015: error occurred in stored script Memory Script-RMAN-06136: ORACLE error from auxiliary database: ORA-17629: Cannot connect to the remote database server-ORA-17627: ORA-12154: TNS:could not resolve the connect identifier specified-ORA-17629: Cannot connect to the remote database server

Cause:

RMAN duplication fails with the error stating tns unable to resolve error

RMAN> duplicate target database for standby from active database using backupset section size 300M nofilenamecheck;

Starting Duplicate Db at 18-JUN-21
using target database control file instead of recovery catalog
allocated channel: ORA_AUX_DISK_1
channel ORA_AUX_DISK_1: SID=1 device type=DISK

contents of Memory Script:
{
   backup as copy reuse
   targetfile  '/oracle/base/product/12.1.0/dbhome_1/dbs/orapworcl' auxiliary format
 '/oracle/base/product/12.1.0/dbhome_1/dbs/orapworcldgp'   ;
}
executing Memory Script

Starting backup at 18-JUN-21
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=66 device type=DISK
Finished backup at 18-JUN-21

contents of Memory Script:
{
   restore clone from service  'orcl' standby controlfile;
}
executing Memory Script

Starting restore at 18-JUN-21
using channel ORA_AUX_DISK_1

RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03002: failure of Duplicate Db command at 06/18/2021 18:58:07
RMAN-05501: aborting duplication of target database
RMAN-03015: error occurred in stored script Memory Script
RMAN-06136: ORACLE error from auxiliary database: ORA-17629: Cannot connect to the remote database server
ORA-17627: ORA-12154: TNS:could not resolve the connect identifier specified
ORA-17629: Cannot connect to the remote database server

Workaround:

I connected and run duplication from auxiliary database instead of running duplicate from target database