Exception occurred: java.sql.SQLException: ORA-28040: No matching authentication protocol

Issue:

while I was running adcfgclone.pl on appsTier and could not connect my database which was upgraded from 10.2.0.5 to 12.1.0.2 

Workaround:

Add SQLNET.ALLOWED_LOGON_VERSION=8 in sqlnet.ora on the db side. 

Retest the issue.