The ORA-12505 error in Oracle SQL Developer
Root cause of the problem:
The most common cause is that the Oracle Database instance has not been started or is not registered with the listener. This generally happens when the computer has been shut down or SQL Developer has not been used for a long time.
Steps to Resolve the problem:
Step 1: Open Command Prompt as Administrator
To ensure you have the necessary permissions to manage database services, you must run the Command Prompt with elevated privileges.
Press the Windows Key, type
cmd.Right-click on Command Prompt and select Run as administrator.
Step 2: Launch SQL*Plus without Logging In
Once the terminal is open, you need to enter the SQL*Plus environment without immediately connecting to a specific database schema.
Type the following command and press Enter:
sqlplus /nolog
Step 3: Connect as a System Administrator (SYSDBA)
Next, you need to connect to the Oracle instance with administrative rights to change its status.
Type the following command:
conn sys as sysdba;When prompted for a password, type the password (e.g.,
admin) and press Enter.Note: For security reasons, the characters will not appear on the screen as you type the password.
If the database is down, you will see a message stating: "Connected to an idle instance."
Step 4: Start the Oracle Instance
Finally, you need to move the database from an idle state to an open state so that SQL Developer can connect to it.
Type the following command and press Enter:
startup
Wait a few moments for the process to complete. You will see several lines of data regarding the System Global Area (SGA), followed by the confirmation message: "ORACLE instance started."
Conclusion
Database is now open and mounted! You can now return to SQL Developer and connect to your database as usual. If you frequently encounter this issue, ensure that your Oracle services are set to "Automatic" in the Windows Services panel.
Check the following for execution process:
