DevOps, CI/CD and Automation

Hi,
There are few issues in the upgrade that might arise concerning logins:
with default install oracle 19 password are case sensitive
The password 'format' changed. You can check in dba_users
You might need to add to sqlnet.ora the parameter SQLNET.ALLOWED_LOGON_VERSION_SERVER=11
look into https://docs.oracle.com/en/database/oracle/oracle-database/18/spmsu/finding-and-resetting-user-passwords-10g-password-version.html#GUID-D7B09DFE-F55D-449A-8F8A-174D89936304
It will cover some of it.
Regards,
Hadar

Thanks Hadar. The password issue I knew about. I added the code to SQLNET.ORA in both the oracle_home/network/admin folder and the instantclient/network/admin folder and now get an ORA-12504 error.
I added both a tnsnames.ora and listener.ora files to both folders (with appropriate settings) but can't get past the 12504 error.
Any ideas? Greatly appreciated!
tnsnames.ora (orcltest is name of database, brian-surface4 is name of PC)
LISTENER_ORCLTEST =
(ADDRESS = (PROTOCOL = TCP)(HOST = Brian-Surface4)(PORT = 1521))

ORACLR_CONNECTION_DATA =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1521))
)
(CONNECT_DATA =
(SID = CLRExtProc)
(PRESENTATION = RO)
)
)

ORCLTEST =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = Brian-Surface4)(PORT = 1521))
(CONNECT_DATA =
(SERVER = DEDICATED)
(SERVICE_NAME = orcltest)
)
)
listener.ora
SID_LIST_LISTENER =
(SID_LIST =
(SID_DESC =
(SID_NAME = CLRExtProc)
(ORACLE_HOME = C:\oracle\WINDOWS.X64_193000_db_home)
(PROGRAM = extproc)
(ENVS = "EXTPROC_DLLS=ONLY:C:\oracle\WINDOWS.X64_193000_db_home\bin\oraclr19.dll")
)
)

LISTENER =
(DESCRIPTION_LIST =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = Brian-Surface4)(PORT = 1521))
(ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1521))
)
)

Just to clarify, do you mean you upgraded the database the app is still at Legacy 11g app client? You are testing this where the database and client are on the same host?