ORA-12154: TNS:could not resolve the connect identifier specified | ORA-12518: TNS:listener could not hand off client connection
ORA-12154 and ORA-12154 generating when you are having issues with database connectivity whenever you try to login into your database. In my scenario, I was trying to install and configure Oracle Enterprise Manager 12c on my local system for pratice purposes and for that I had installed repository database named as EMCTLDB. This is a 12c database where EMCTLDB is the CDB name and EMCTLPDB is the PDB name. After the database was installed, I made the entries in the LISTENER.ORA and TNSNAMES.ORA like this,