Oracle SQL Developer: Failure - Test failed: The Network Adapter could not establish the connection?

Question

Problem

Please note that I changed details for security purposes. However, the problem remains intact.

I installed an Oracle 11g database on a server at l

Answer 1

I just had same issue when I installed the oracle 11g and then creating the database.

I don't even know that the listener has to create manually. Hence, I open Net Configuration Assistant and manually create the listener.

And I can connect the database that I created locally through sql developer.

Answer 2

I faced the same problem. I had to turn off my firewall, then it worked.

You could also open the port: http://windows.microsoft.com/en-in/windows/open-port-windows-firewall#1TC=windows-7

Answer 3

I am answering this for the benefit of future community users. There were multiple issues. If you encounter this problem, I suggest you look for the following:

• Make sure your tnsnames.ora is complete and has the databases you wish to connect to
• Make sure you can tnsping the server you wish to connect to
• On the server, make sure it will be open on the port you desire with the specific application you are using.

Once I did these three things, I solved my problem.

Answer 4

I had a similar issue where I also continuously got the same error. I tried many things like changing the listener port number, turning off the firewall etc. Finally I was able to resolve the issue by changing listener.ora file. I changed the following line:

(ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1521))

to

(ADDRESS = (PROTOCOL = TCP)(HOST = hostname)(PORT = 1521)) 

I also added an entry in the /etc/hosts file.

you can use Oracle net manager to change the above line in listener.ora file. See Oracle Net Services Administrator's Guide for more information on how to do it using net manager.

Also you can use the service name (database_name.domain_name) instead of SID while making the connnection.

I Hope it helps.

Answer 5

Curiously, I was able to solve the same issue by doing the exact opposite move to svc's ! I had to :

1) replace the FQDN hostname in my tnsnames.ora / listener.ora files with localhost, and restart the listener service, and

2) two, I had to use "SYS as SYSDBA" as the username in the SQL Developer input textbox

to finally be able to have SQL Developer hook to my local instance.

Answer 6

This worked for me. may help some one. Turn off firewall. on RHEL 7

systemctl stop  firewalld