How can I change the connection descriptor used by Oracle Enterprise Manager? I've recently changed the SERVICE_NAME of my 11g database and Enterprise Manager can no longer connect to it:


  2014-01-08 10:36:06,047 [HTTPThreadGroup-3] ERROR eml.OMSHandshake
  processFailure.806 - OMSHandshake failed.(AGENT URL =
  https://Test9.lab.nyc-14.knoa.com:3938/emd/main)(ERROR =
  INTERNAL_ERROR)(CAUSE =java.sql.SQLException: Listener refused the
  connection with the following error: ORA-12514, TNS:listener does not
  currently know of service requested in connect descriptor The
  Connection descriptor used by the client was:
  (DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST=Test9.lab.nyc-14.knoa.com)(PORT=1521)))(CONNECT_DATA=(SERVICE_NAME=test9.lab.nyc-14.knoa.com))))


The SERVICE_NAME in there is indeed the old one. I've updated NETWORK\ADMIN\tnsnames.ora but that didn't fix it. Where does Enterprise Manager read the connection descriptor from?
I'm guessing because you haven't specified what version of OEM you're using.

If you're using OEM 12C, go to the DB home then click on "Oracle Database", "Target Setup", "Monitoring Configuration".  You can change the SID there.