Still using Oracle Designer?
And the Windows version has to be updated?
And the Oracle Database version as well?

Don’t Panic! It still works.

Install Oracle Designer with the Installer or Setup set on compatibility WinXP and run as Administrator.

You will find all the registry key now under:

When using Oracle Database 12c you will get an error when using the Oracle Designer java-based utilities, such as version compare.
The underlying error is: ORA-28040
This can be solved by adding the following entries to the sqlnet.ora in the ORACLE_HOME/network/admin folder of the database on the database server:

now the jdbc drivers in the can connect to the Oracle 12c database.

Have Fun !