ORA-28040: No matching authentication protocol, when connecting to a 12c DB

The issue:

 >sqlplus myuser/mypass@MY12CDB

SQL*Plus: Release 11.2.0.2.0 Production on Fri May 11 10:22:44 2018

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ERROR:
ORA-28040: No matching authentication protocol


 Cause: connecting to a 12c DB, with a client lower than 11.2.0.3

 Solution:

 Add the following to $ORACLE_HOME/network/admin/sqlnet.ora , for both versions:

 SQLNET.ALLOWED_LOGON_VERSION_SERVER=8
 SQLNET.ALLOWED_LOGON_VERSION_CLIENT=8

Note: it's important to modify the sqlnet.ora in the above mentioned location.