Description: ORA-12154: TNS:could not resolve the connect identifier for a specific database after successful completion of patching cycle of Exadata Fleet Update collection of databases on Oracle Exadata Database Service on Dedicated Infrastructure (ExaDB-D).

<Database home>/bin/sqlplus <db_user>/<db_pass>@<tns service name>
SQL*Plus: Release x.x.x.x.x
Version x.x.x.x.x
Copyright (c) 1982, 2022, Oracle.  All rights reserved.
ERROR:
ORA-12154: TNS:could not resolve the connect identifier specified
Enter user-name:

Action: Copy the files from old Oracle home of the specific database to the current Oracle home.

cp <old_oracle_home>/network/admin/<dbname>/* <current_oracle_home>/network/admin/<dbname>/

Description: Applying a database patch fails when the parameter WALLET_LOCATION or ENCRYPTION_WALLET_LOCATION and its value in the sqlnet.ora file is split or broken as follows:

WALLET_LOCATION= 
(SOURCE= (METHOD=FILE) 
(METHOD_DATA=(DIRECTORY=/var/opt/oracle/dbaas_acfs/grid/tcps_wallets)))
ENCRYPTION_WALLET_LOCATION= 
(SOURCE= (METHOD=FILE) 
(METHOD_DATA=(DIRECTORY=/var/opt/oracle/dbaas_acfs/ST1001DB/wallet_root/tde)))

Action: Modify the affected sqlnet.ora file as follows to ensure that the parameters WALLET_LOCATION and ENCRYPTION_WALLET_LOCATION and their values remain on the same line.

WALLET_LOCATION= (SOURCE= (METHOD=FILE) 
(METHOD_DATA=(DIRECTORY=/var/opt/oracle/dbaas_acfs/grid/tcps_wallets)))
ENCRYPTION_WALLET_LOCATION= (SOURCE= (METHOD=FILE) 
(METHOD_DATA=(DIRECTORY=/var/opt/oracle/dbaas_acfs/ST1001DB/wallet_root/tde)))

Action: Update security rules as follows:

• Stateless: No (all rules must be stateful)
• Source Type: CIDR
• Source CIDR: Client subnet's CIDR
• IP Protocol: TCP
• Source Port Range: All
• Destination Port Range: 7085
• Description: Optionally, add a meaningful description of the rule. For example, Allow access to Exadata Fleet Update private endpoint within the subnet.

To prevent rollback failures when reverting from 23.7 to 23.5, apply the following workaround:

1. Apply Patch 37547027 as a one-off to the 23.5 DB Home using OPatch apply.
2. Proceed with the rollback operation from 23.7 to 23.5 after applying the fix.

If you encounter the following error in the datapatch output while rolling back from 23.7 to 23.5, follow the steps below to resolve it.

Error: prereq checks failed!
patch 36741532: Value of ru_version is undefined in dba_registry_sqlpatch_ru_info in PDB PDB$SEED

1. Set the environment variables

   export ORACLE_HOME="<targetHomePath>"
   export ORACLE_SID="<DBSID>"

2. Connect to SQL*Plus as SYSDBA

   $ORACLE_HOME/bin/sqlplus / as sysdba

3. Open PDB$SEED in Read-Write mode

   alter session set "_oracle_script"=true;
   alter pluggable database pdb$seed close instances=all;
   alter pluggable database pdb$seed open read write instances=all;

4. Switch to PDB$SEED and check for errors

   alter session set container=pdb$seed;
   select * from dba_errors;

   You may encounter errors such as:

   PLS-00907: cannot load library unit SYS.SYS_STUB_FOR_PURITY_ANALYSIS (referenced by SYS.GETLONG)

5. Compile required packages

   alter package SYS.SYS_STUB_FOR_PURITY_ANALYSIS compile;
   show errors;  -- Should return "No errors."

   alter package dbms_lob compile body;
   show errors;  -- Should return "No errors."

   Run the following query to verify that no errors remain:

   select * from dba_errors;

6. Close and reopen PDB$SEED in Read-Only mode

   alter pluggable database pdb$seed close instances=all;
   alter pluggable database pdb$seed open read only instances=all;

7. Exit SQL*Plus

   exit;

8. Run datapatch to apply SQL patches

   $ORACLE_HOME/OPatch/datapatch -verbose

   If you have multiple PDBs and want to distribute the patching workload across nodes, you can use the -pdbs option.

9. Restart the database

   # Stop the database
   srvctl stop database -d <DB_NAME>

   # Start the database
   srvctl start database -d <DB_NAME>

10. Verify PDB state

    After restarting, all PDBs should come out of RESTRICTED mode, and the rollback to 23.5 should be successful.