Capture, Read and Poster process can encounter this issue. This can also happen during ora_setup or ora_cleansp.
oerr ORA 12154
12154, 00000, "TNS:could not resolve the connect identifier specified"
// *Cause: A connection to a database or other service was requested using
// a connect identifier, and the connect identifier specified could not
// be resolved into a connect descriptor using one of the naming methods
// configured. For example, if the type of connect identifier used was a
// net service name then the net service name could not be found in a
// naming method repository, or the repository could not be
// located or reached.
Resolution 1:
Check and correct ORACLE_SID entries in /etc/oratab (/var/opt/oracle/oratab) (for Windows check the Registry entries as appropriate)
Resolution 2:
In RAC environments (or if you use a SQLNET connection instead of BEQ) re-run ora_setup with correct TNS_ALIAS.
