ORA-12560: TNS: protocol adapter error
 

Question:  I installed Oracle 10g on my server but there is a problem with error "ORA-12560:TNS:protocol adapter error".  When I sign on I get the error "ORA-12560:TNS:protocol adapter error"...

Enter password:
ERROR:  ORA-12560: TNS:protocol adapter error

Enter password:
ERROR:  ORA-12560: TNS:protocol adapter error

Enter password:
ERROR:  ORA-12560: TNS:protocol adapter error

Enter password:
ERROR:  ORA-12560: TNS:protocol adapter error

Enter password:
ERROR:  ORA-12560: TNS:protocol adapter error

Enter password:
ERROR:  ORA-12560: TNS:protocol adapter error

Answer by Edward Stoever:

Is there a listener running? Have you run the netca program to configure and start the listener?  The Oracle docs note that you should troubleshoot the ORA-12560 by tracing the connection:

ORA-12560: TNS: protocol adapter error
 
Cause: A generic protocol adapter error occurred.

Action: Check addresses used for proper protocol specification. Before reporting this error, look at the error stack and check for lower level transport errors. For further details, turn on tracing and re-execute the operation. Turn off tracing when the operation is complete.

If you are running Oracle on Windows, you may fi the ORA-12560 by running the oradim utility to create a service for the listener.

MOSC Note: 117976.1 offers tips for diagnosing the TNS-12560 error noting that the TNS-12560 is in the TNS transport layer and the TNS-12560 may only be a symptom of a lower-level network error as listed in MOSC Note 39662.1. 

You can use MOSC Note 39774.1 to get a SQL*Net trace or follow these instructions for getting a SQL*Net trace.