Some DBCA operations require to read and parse the net admin files, TNSNAMES.ORA, LISTENER.ORA and SQLNET.ORA.If there is any syntax issues with those files, including control characters, etc, Then the operation can fail.
Use the GUI Net manager tool to check which file has the problem.Select
1. Open Net Manager tool (NetMGR)
2. Click on Local, then click on Profile. This is the Sqlnet.ora file settings. If the drop down button on right hand panel, Naming, General, etc works, showing values for the parameters, that as set, the file can be read.Otherwise, rename Sqlnet.ora and rebuild using Net Manager.
3. Click on Service Naming.You should be able to see all the service names in your tnsnames.ora file. If clicking on any of the entries returns an error, then delete and recreate the entry. If no entries are returned, rename the Tnsnames.ora and rebuild using Net Manager.
4. Click on Listener and select the listener name. If nothing is returned, then the Listener.ora file needs to be rebuilt. Rename / move the listener.ora file and use Net Manager to build new listener.
Ensure any action to recreate, change entry is saved by Net Manager, via File, Save Network Configuration
Use Net Manager to create and edit the sqlnet.ora file.
Do not edit the sqlnet.ora file manually.