ORA-01031: insufficient privileges while connecting as sqlplus / as sysdba.

 [ora@ora_oracle]$ sqlplus / as sysdba

SQL*Plus: Release 11.1.0.7.0 - Production on Mon Oct 19 04:10:36 2020

 Copyright (c) 1982, 2008, Oracle.  All rights reserved.

ERROR:

ORA-01031: insufficient privileges

============OR=============

[oracle@ora-dev ~]$ sqlplus / as sysdba

 SQL*Plus: Release 12.2.0.1.0 Production on Mon Oct 19 04:15:30 2020

 Copyright (c) 1982, 2016, Oracle.  All rights reserved.

 ERROR:

ORA-01017: invalid username/password; logon denied

Solution :-

 Check the value of the SQLNET.AUTHENTICATION_SERVICES parameter in file $ORACLE_HOME/network/admin/SQLNET.ORA

Add below parameter in SQLNET.ora file

SQLNET.AUTHENTICATION_SERVICES = (BEQ,)

SQLNET.ALLOWED_LOGON_VERSION_SERVER = 10

SQLNET.ALLOWED_LOGON_VERSION_CLIENT = 10

Note :- No need to restart DB as well as Listener.