Getting ORA-12560 with Oracle Express 10g

I started to receive this error while I`m using C# with Oracle 10g.

ORA-12560 and I really need to solve it as I`m running out of 开发者_JAVA技巧time on my grad project.

ORA-12560 is a configuration issue. This makes it difficult to diagnose remotely. I have answered a similar question on SO before. my advice is general enough that it should help you too. Find out more.

If it doesn't you'll need to post more details of your listener.ora, tnsnames.ora and perhaps your hosts files.

edit

"All the files are hosted here:"

Hmmmm. Both listener.ora andtnsnames.ora reference HOST = SIKAS-TOSH but server is not included in the hosts file.

edit 2

"the Oracle 10g Express Edition is installed on my PC"

If your database is on your PC then the files on some web-server are irrelevant. It is the listener.ora andtnsnames.ora on your PC which matter. Those versions of the file need to reference HOST = localhost or else your hosts needs to include SIKAS-TOSH as an alias for 127.0.0.1.

Make sure your listener is running. If it is, try restarting it and re-registering your database with it (through sqlplus as sysdba, type the command alter system register;). Also, make sure that if you run a local firewall you have allowed the port 1521 for incoming traffic (or your custom port if you have changed this).

In Windows the listener is a service, prefixed with the oracle home name + TNSListener. In Linux, set your oracle home environment and type:

lsnrctl stop
lsnrctl start

I have unintalled and re-installed the oracle 10g many times as well as the ODAC112011beta, last time I didn`t install the ODAC112011beta, instead, I used the Oracle.DataAccess.Client file found in the C:\oraclexe\app\oracle\product\10.2.0\server\BIN\Oracle.DataAccess.dll ... then I started the service from START->All Programs->Oracle Database 10g Express Edition->Start Database as administrator ... now I can connect to the Oracle through C# ... I hope I face no more problems