ora-12514 Error While Connecting local Oracle EXPRESS EDITION 11
ORA-12514 means there is no requested service registered in the listener.

ORA-12505 means there is no requested instance registered in the listener.

If the service name or instance name you provided was correct, then your database may be not started.

Oracle databases run as a service on Windows named OracleServiceXE (for Express Edition), you should check and start the service if it is not running.

On Linux, you can start the database as:

sqlplus / as sysdba
SQL&gt; startup


After that you should see your instance and services in the output of lsnrctl status, and that is when you should try connecting again.