Short post on a error which can take lot of time to debug. You have upgraded a database and after restoring all files (init,tnsnames) try to startup 11g database and it fails with following error
SQL> startup nomount ORA-00119: invalid specification for system parameter REMOTE_LISTENER ORA-00132: syntax error or unresolved network name 'scan-clu:1521'
11gR2 requires remote_listener to be set to <scan_name:port>. Problem is that the sqlnet.ora file has been modified/replaced (from earlier version backup) which does not have EZCONNECT and has only TNSNAMES. Ensure that your sqlnet.ora file contain's EZCONNECT
NAMES.DIRECTORY_PATH= (TNSNAMES, EZCONNECT)