Windows – connection issue / Oracle Express 11g in windows7 32bit

oracleoracle-11g-r2windows

I have an issue with Oracle Express 11g in windows7 32bit.
Everytime when I try to conncet to the database I get this error message.
How can I fix it please!

Oracle Express 11g

Best Answer

You most likely need to set the ORACLE_SID environment variable. This error usually means you are trying to connect to a database that doesn't exist. Also check that ORACLE_HOME is set correctly. If that doesn't fix it, check if the database service is started. If it is, check the alert log for error messages.