I am using arcgis desktop 10.1 and oracle 11gR2, connected using direct connect, there is no app server and there is no service. When i try to upgrade gdb, i get following error in the log.
[Mon Feb 19 08:45:19 2018]
ST_Geometry Schema Owner: (SDE) Type Release: 1007
[Mon Feb 19 08:45:19 2018] Instance initialized for ((sde)) . . .
[Mon Feb 19 08:45:19 2018] Error: Underlying DBMS error (-51).
[Mon Feb 19 08:45:19 2018] Error: DB_arcsde_setup: Unable to connect
[Mon Feb 19 08:45:19 2018] ORA-00933: SQL command not properly ended
[Mon Feb 19 08:45:19 2018] ERROR installing/upgrading ArcSDE, Error = -51