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
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.