Oracle listener not running and won't start

Question

I am getting the following errors while from the lsnrctl status command:

C:\\Users\\pna105>lsnrctl stat

 LSNRCTL for 64-bit Windows: Version 11.         


        

Answer 1

In my case, I tried to start the listener via console:

> lsnrctl star

This command printed the following error:

TNS-12560: TNS:protocol adapter error
TNS-00583: Valid node checking: unable to parse configuration parameters

So, I performed the following actions:

1. Check if Oracle listener.ora or sqlnet.ora file contains special characters
2. Check if Oracle listener.ora or sqlnet.ora` file are in wrong format or syntax
3. Check if Oracle listener.ora or sqlnet.ora file have some left justified parenthesis which are not accepted by oracle parser.

Have a look at these files and check the proper syntax. If possible remove/rename sqlnet.ora and try to restart the listener. Or remove/rename both listener.ora or sqlnet.ora file and recreate it properly. These will defenitely resolve the issue.