ORA-12543: TNS:destination host unreachable but telnet and tnsping works

Question

Last days i stay face to face with a strange oracle problem. I have defined database in tnsnames.ora. Oracle client is installed , client and client/bin have been added to PATH.

Ping works, tnsping works, I can connect to host by database port with telnet.

When I try to run application that tries to connect to db I got

ORA-12543: TNS:destination host unreachable

It is the same situation when I try to connect by sqlplus

sqlplus username/password@TNSNAME

Situation occurred only on one workstation, it's mean in common it should works.

WS is windows 7 64 bit.
Database :

Oracle Database 10g Enterprise Edition Release 10.2.0.5.0 - 64bit Production

Answer 1

I also faced the same issue ORA-12543: TNS:destination host unreachable

i resolved it in this way

open sqlplus

connect

enter user-name :system enter password : HHHHH@2014

then the following error raised

the problem is my password contains @ symbol

resolved it by putting my password in "HHHHHH@2014"

Answer 2

I was having the same problem, I resolved it by changing my password and removing "@" character. It worked for me.

@ is to tell SQL plus which connection identifier (service name/sid) we want to connect. In short, avoid using this character in password.