Sometimes you try to login to your Oracle XE on your home computer, and get this curt blocking response:
Here’s the top reason why it might happen and how to fix it.
Database is not up
The first thing to check: is the Oracle service running? If you are seeing ORA-12560:TNS protocol adapter error, the Oracle service you are trying to connect to is most likely not running.
How to check:
On a Windows machine, go to Start –> Run, type services.msc and click Enter on the keyboard.
This will open the Services window. Locate the service for Oracle database under the Name column – OracleServiceXE in this case. For the connection to work, the status must be "Started".
As you see, the status here is NOT Started.
Start the service:
Click the link "Start" the service under the service name.
Once done, the status will change to Started.
Try logging in next. Lo and behold – ORA-12560:TNS protocol adapter error has vanished. You can now login!
If you use this Oracle service regularly, set the service Startup Type to "Automatic". This will ensure that the database service comes up automatically whenever you restart your machine.