Check the below:
1. check groups for oracle user.
2.check password file is proper or not.
3. Try to see this line, SQLNET.AUTHENTICATION_SERVICES = (NTS), in sqlnet.ora file if exists. If yes, comment that and try to connect using / as sysdba.
1. check groups for oracle user.
2.check password file is proper or not.
3. Try to see this line, SQLNET.AUTHENTICATION_SERVICES = (NTS), in sqlnet.ora file if exists. If yes, comment that and try to connect using / as sysdba.
