Cannot connect to PDB

[big]

Hi,

On R12.2.9 DB 19c on AIX (PDB is our e-business database)

On DB server cannot connect to PDB:

sqlplus system@PDB
ORA-12154: TNS:could not resolve the connect identifier specified

tnsping PDB
TNS-03505: Failed to resolve name
Some facts:
SQL> SELECT name, open_mode from v$pdbs;
NAME         OPEN_MODE
-------------------- ------------------------------
PDB$SEED       READ ONLY
PDB       READ WRITE
grep PDB /u01/product/oracle/distrib/ora19300/db/network/admin/tnsnames.ora

PDB=
                (SERVICE_NAME=ebs_PDB)
PDB_FO=
                (SERVICE_NAME=ebs_PDB)
PDB_BALANCE=
                (SERVICE_NAME=ebs_PDB)
PDB_REMOTE=
             (ADDRESS=(PROTOCOL=IPC)(KEY=EXTPROCPDB))

But on Application server node we can connect to PDB:
sqlplus system@PDB
password:
Connected.
What is your diagnosis?

Thanks.

[ErmanArslansOracleBlog]

What is written in your tnsnames file placed in your db tier? What are the TNS entries there? Probably your PDB tns entry is something different there, check and then connect your PDB using the correct TNS. (or you may have a wrong shell environment.. that 's may be the reason.. That may lead your sqlplus read the wrong tnsnames file.)

Here is an example for EBS PDB connection ->

How to connect the Oracle E-Business Suite PDB as SYSTEM user?
Run the following commands to connect PDB as SYSTEM user
$ source <PDB_NAME>_<NODE_NAME>.env
$ sqlplus system/manager@<PDB_NAME>