Christoph Jahn

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Oracle Error 17002 “Io Exception: The Network Adapter could not establish the connection”

If you search for the Oracle error “Io Exception: The Network Adapter could not establish the connection” (ORA-17002) you will find plenty of discussion on the web. It usually comes down to what the message says, that is a network issue. But the error can also be caused by e.g. incompatible jar files. In my case, however, I was trying to access a 11g R2 instance from SQL Developer and during initial setup everything had worked. And local access, also with SQL Developer, worked absolutely fine.

Solution: Replace “simple” DB hostname with the fully qualified one. I am not sure why this changed the behavior. I can think of either a DNS setup issue (although my search list included the domain) or some kind of reverse lookup logic that is being applied. Anyway, I wanted to share this finding and also record it for my own future use.


Comment from Exether posting from
Time June 3, 2011 at 13:22

Thanks for the tip, it worked for me too !!
Even, I changed localhost to my machine name, it worked, and it was still working when I reverted to localhost. There must be some strange network behaviour beneath.

Comment from enxel posting from
Time August 17, 2011 at 19:33

thank you very much!
I tried a lot of complex solutions and this was the winner, now I can continue my work, thanks again

Comment from mahendra posting from
Time November 2, 2011 at 11:52

thank you very much …!

Comment from sinan posting from
Time November 22, 2011 at 09:33

other solution :
you make sure that you have the right DNS on your IP Address this is happened if you have 2 network

Good luck

Comment from Aneeq posting from
Time February 15, 2012 at 15:57

It didn’t work for me.

Comment from Neil posting from
Time April 9, 2012 at 19:56

Thank you very much, it helped me to solve the problem I had

Comment from wardi-ahamed posting from
Time April 12, 2012 at 18:37

Thank you so much for your helping me.

Comment from kamel posting from
Time April 21, 2012 at 12:25

it worked fo me too ! merci beacoup !!

Comment from Ravi Joshi posting from
Time May 18, 2012 at 12:53

Awesome tip! worked for me too…it was a dns issue

Comment from Vedran posting from
Time September 13, 2012 at 22:24

Hey, what’s the difference between “simple DB hostname” and “fully qualified DB hostname”? some example pls because I’m not sure did I understand it right? :)

Comment from Christoph Jahn posting from
Time September 16, 2012 at 17:34

Simple name is e.g. “dbserver” whereas fully qualified one is “”. Does that help?

Comment from Hope posting from
Time September 18, 2012 at 14:48

Where can I find fully qualified name? I tried with select * from global_name, but I got same name as simple name….

thank you

Comment from Christoph Jahn posting from
Time September 19, 2012 at 19:03

The fully qualified hostname is part of the machine’s network setup and only indirectly part of Oracle

Comment from Rao posting from
Time October 30, 2012 at 09:01

It worked like a charm!!!Thanks

Comment from Deepak R posting from
Time November 12, 2012 at 10:07

Awesome tip!!! It worked for me..

Comment from praveen posting from
Time November 24, 2012 at 16:59

I tried everything, it doesn’t work. Finally i tried by using connection type as local/Bequeath. Then it worked for me.

Comment from Lucas Silva posting from
Time February 20, 2013 at 19:31

Other solution: In your application data-source change the connect string from
“jdbc:oracle:thin:@host:port:sid” (short connection string)


“jdbc:oracle:thin:@(DESCRIPTION= (ADDRESS = (PROTOCOL = TCP)
(HOST = host)
(PORT = port)
)” (full server string)

Comment from ennovation posting from
Time May 12, 2014 at 17:41

Super… Used the fully qualified hostname and it worked. Thanks.

Comment from Saqib Mustafa Abbasi posting from
Time May 23, 2014 at 09:40

Thanks worked for me :)

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