Resolving ora-01017 invalid username/password logon denied in 12c R2

Resolving ora-01017 invalid username/password logon denied 12c

After upgrade to Oracle 12c R2 the

SQLPLUS system/pwd@orcl failed with
ora-01017 invalid username/password logon denied 12c sysdba

Resolution:

Step 1.Check password version of users:

SQL>select DISTINCT password_versions as versions from SYS.dba_users;

10G 11G < case insensitive password
10G        < case sensitive password

SQL>ALTER SYSTEM SET sec_case_sensitive_logon = FALSE SCOPE = BOTH;
and try again, if still not able to login then try Step 2.

Step 2. if step 1 fails then add the following line in SQLNET.ORA file

SQLNET.ALLOWED_LOGON_VERSION_CLIENT=8
SQLNET.ALLOWED_LOGON_VERSION_SERVER=8