I Installed Oracle 12C forms.
When I try to run FRMBLD,I get the following error:
FRM-18122:Oracle Forms Debugger failed to initialize.
I click on Ok.
Under the Data Block Wizard when trying to connect, I get the following error:

ORA-12154: TNS:could not resolve the connect identifer specified.

I am enclosing a copy of the tnsnames.ora, sqlnet.ora and listiner.ora file with the results of the listener file.

ORA-12154: TNS:could not resolve the connect identifier specified
 *Cause:  A connection to a database or other service was requested using
 a connect identifier, and the connect identifier specified could not
 be resolved into a connect descriptor using one of the naming methods
 configured. For example, if the type of connect identifier used was a
 net service name then the net service name could not be found in a
 naming method repository, or the repository could not be
 located or reached.
 *Action:
   - If you are using local naming (TNSNAMES.ORA file):
      - Make sure that "TNSNAMES" is listed as one of the values of the
        NAMES.DIRECTORY_PATH parameter in the Oracle Net profile
        (SQLNET.ORA)
      - Verify that a TNSNAMES.ORA file exists and is in the proper
        directory and is accessible.
      - Check that the net service name used as the connect identifier
        exists in the TNSNAMES.ORA file.
      - Make sure there are no syntax errors anywhere in the TNSNAMES.ORA
        file.  Look for unmatched parentheses or stray characters. Errors
        in a TNSNAMES.ORA file may make it unusable.
   - If you are using directory naming:
      - Verify that "LDAP" is listed as one of the values of the
        NAMES.DIRETORY_PATH parameter in the Oracle Net profile
        (SQLNET.ORA).
      - Verify that the LDAP directory server is up and that it is
        accessible.
      - Verify that the net service name or database name used as the
        connect identifier is configured in the directory.
      - Verify that the default context being used is correct by
        specifying a fully qualified net service name or a full LDAP DN
        as the connect identifier
   - If you are using easy connect naming:
      - Verify that "EZCONNECT" is listed as one of the values of the
        NAMES.DIRETORY_PATH parameter in the Oracle Net profile
        (SQLNET.ORA).
      - Make sure the host, port and service name specified
        are correct.
      - Try enclosing the connect identifier in quote marks.

   See the Oracle Net Services Administrators Guide or the Oracle
   operating system specific guide for more information on naming.

The TNSNAMES.ORA is in the proper directory.
All the syntax looks correct and there is no unmatched parentheses or stray characters.
I am not using LPAD or EZCONNECT.
I added the pdborcl to the TNSNAMES.ORA file.
I put the TNSNAMES.ORA IN THE FORMS HOME and changed the path in the Environmant Variables file under the System variables group
with the same results.

Here is my tnsping alias and the listener status:

C:\Users\Windows 7>tnsping orcl

TNS Ping Utility for 64-bit Windows: Version 12.1.0.2.0 - Production on 18-MAR-2019 09:05:56

Copyright (c) 1997, 2014, Oracle. All rights reserved.

Used parameter files:
C:\ORACLE_12C_DATABASE\product\12.1.0\dbhome_1\network\admin\sqlnet.ora


Used TNSNAMES adapter to resolve the alias
Attempting to contact (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1521)) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = orcl)))
OK (40 msec)

C:\Users\Windows 7>lsnrctl status

LSNRCTL for 64-bit Windows: Version 12.1.0.2.0 - Production on 18-MAR-2019 09:06:30

Copyright (c) 1991, 2014, Oracle. All rights reserved.

Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=localhost)(PORT=1521)))
STATUS of the LISTENER
------------------------
Alias LISTENER
Version TNSLSNR for 64-bit Windows: Version 12.1.0.2.0 - Production
Start Date 16-MAR-2019 13:24:41
Uptime 1 days 19 hr. 41 min. 49 sec
Trace Level off
Security ON: Local OS Authentication
SNMP OFF
Listener Parameter File C:\ORACLE_12C_DATABASE\product\12.1.0\dbhome_1\network\admin\listener.ora
Listener Log File C:\ORACLE_12C_DATABASE\diag\tnslsnr\Window10PRO\listener\alert\log.xml
Listening Endpoints Summary...
(DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=127.0.0.1)(PORT=1521)))
(DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(PIPENAME=\\.\pipe\EXTPROC1521ipc)))
(DESCRIPTION=(ADDRESS=(PROTOCOL=tcps)(HOST=Window10PRO)(PORT=5500))(Security=(my_wallet_directory=C:\ORACLE_12C_DATABASE\admin\orcl\x db_wallet))(Presentation=HTTP)(Session=RAW))
Services Summary...
Service "CLRExtProc" has 1 instance(s).
Instance "CLRExtProc", status UNKNOWN, has 1 handler(s) for this service...
Service "orcl" has 1 instance(s).
Instance "orcl", status READY, has 1 handler(s) for this service...
Service "orclXDB" has 1 instance(s).
Instance "orcl", status READY, has 1 handler(s) for this service...
Service "pdborcl" has 1 instance(s).
Instance "orcl", status READY, has 1 handler(s) for this service...
The command completed successfully

Here is my tnsping alias and the listener status:

I added pbdorcl to the tnsnames.ora file in the forms directory:

pdbORCL =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1521))
(CONNECT_DATA =
(SERVER = DEDICATED)
(SERVICE_NAME = pdborcl)
))

Really?
host points to where the DB host is. If it's on the same machine as the client then what would you put in client tnsnames other than localhost?

I had the variable set to C:\ORACLE_12C_DATABASE\PRODUCT\12.1.0\DBHOME_1\NETWORK\ADMIN

I had the variable set to C:\ORACLE_12C_DATABASE\PRODUCT\12.1.0\DBHOME_1\NETWORK\ADMIN

Wideminnow6970 wrote on Thu, 21 March 2019 16:26

I had the variable set to C:\ORACLE_12C_DATABASE\PRODUCT\12.1.0\DBHOME_1\NETWORK\ADMIN

That's nice.

Please realize & understand that FORMS has it own ORACLE_HOME tree & uses the tnsnames.ora file from under it.

So I am not surprised that the error for FORMS still occurs when you have NOT corrected the underlying problem.

Oracle error message & code is how it informs you that a problem exists.

I had the variable set to C:\ORACLE_12C_DATABASE\PRODUCT\12.1.0\DBHOME_1\NETWORK\ADMIN

Wideminnow6970 wrote on Thu, 21 March 2019 23:26

I had the variable set to C:\ORACLE_12C_DATABASE\PRODUCT\12.1.0\DBHOME_1\NETWORK\ADMIN

I'll try again. You have to provide complete information. In this case, where did you set this variable? It would need to be in the registry, so that all shells can pick it up.
You have not shown a tnsping of pdbrcl.
You have not shown how you have configured Forms to use pdborcl.

The variables were set in the Environment Variable screen:
tns_admin = C:\ORACLE\product\12.1.0\dbhome_1\NETWORK\ADMIN\TNSNAMES.ORA
forms_Path = C:\ORACLE\Middleware\Oracle_Home\forms\java\frmall.jar;C:\ORACLE\Middleware\Oracle_Home\forms\java\FRMWEBUTIL.JAR
forms_builder_classpath = c:\ORACLE\Middleware\Oracle_Home\bin\frmbld.exe;C:\ORACLE\Middleware\Oracle_Home\forms\templates\config\DEFAULT.ENV

Here is the tnsping of pdbrcl:
C:\Users\Windows 7>TNSPING PDBRCL

TNS Ping Utility for 64-bit Windows: Version 12.1.0.2.0 - Production on 01-MAY-2019 15:27:40

Copyright (c) 1997, 2014, Oracle. All rights reserved.
Used parameter files:
C:\ORACLE\product\12.1.0\dbhome_1\network\admin\sqlnet.ora

TNS-03505: Failed to resolve name

Hopefully this is all that you need