Hi guys, I am not an absolute newbie, and have been using the oracle database for a long time. All of a sudden today I am getting the error. ORA-12154: TNS: could not resolve the connect identifier specified This error is obviously related to tnsnames.ora file and not correct Service and SID identifiers. However what's baffling me is that both my tnsnames.ora and listener.ora have the correct entries and even the listener service is running. Here's my tnsnames.ora and here's the listener.ora I am using the service ORCL to connect to the database using SQL Plus. I connected yesterday and it was fine. So i am completely baffled! HAs anyone faced anything like this before?