Error Message = ORA-12514: Cannot connect to database.

 I recently encountered a situation where one of my free Oracle autonomous cloud database was throwing Error Message = ORA-12514: Cannot connect to database, while connecting to the database, the reason was simple - The database was hibernated in cloud because i did not access from a long time.

Here is the full error details -

SQLcl: Release 24.4 Production on Thu May 15 23:44:45 2025

Copyright (c) 1982, 2025, Oracle.  All rights reserved.

Connection failed

  USER          = admin

  URL           = jdbc:oracle:thin:@(description= (retry_count=20)(retry_delay=3)(address=(protocol=tcps)(port=1522)(host=adb.ap-mumbai-1.oraclecloud.com))(connect_data=(service_name=re2d3bgg7ywwtp7_pydb_medium.adb.oraclecloud.com))(security=(ssl_server_dn_match=yes)))

  Error Message = ORA-12514: Cannot connect to database. Service re2d3bgg7ywwtp7_pydb_medium.adb.oraclecloud.com is not registered with the listener at host adb.ap-mumbai-1.oraclecloud.com port 1522. (CONNECTION_ID=qI3rAjuSRe+lAwcEvdtwcg==)

https://docs.oracle.com/error-help/db/ora-12514/

Solution :- Start the database from cloud console and try again after the database is started -

SQLcl: Release 24.4 Production on Thu May 15 23:48:44 2025

Copyright (c) 1982, 2025, Oracle.  All rights reserved.

Last Successful login time: Thu May 15 2025 23:48:45 +05:30

Connected to:

Oracle Database 23ai Enterprise Edition Release 23.0.0.0.0 - for Oracle Cloud and Engineered Systems

Version 23.8.0.25.05

SQL> show user

USER is "ADMIN"

# So there you go , this is how you fix the Error Message = ORA-12514: Cannot connect to database