ORA-01017: invalid username/password; logon denied for SYS user

Hi Team,

when am trying to connect to database as SYS its giving ORA-01017.

[oracle@test~]$ . oraenv

ORACLE_SID = [oracle] ? vcrsd01

The Oracle base has been set to /u01/app/oracle

[oracle@test~]$ sqlplus "/as sysdba"

SQL*Plus: Release 12.1.0.2.0 Production on Tue May 1 23:43:53 2018

Copyright (c) 1982, 2014, Oracle.  All rights reserved.

ERROR:

ORA-01017: invalid username/password; logon denied

But am able to connect when provided the password

[oracle@test~]$ sqlplus

SQL*Plus: Release 12.1.0.2.0 Production on Tue May 1 23:57:14 2018

Copyright (c) 1982, 2014, Oracle.  All rights reserved.

Enter user-name: sys as sysdba

Enter password:

Connected to:

Oracle Database 12c Enterprise Edition Release 12.1.0.2.0 - 64bit Production

With the Partitioning, Automatic Storage Management, OLAP, Advanced Analytics