Only one new feature has been added to Django 1.2.4, a setting to assist in testing databases. Please read the Release Notes for more information. Other than the one feature, Django 1.2.4 is a bug fix and security release.
The official Release Notes for Django 1.2.4 are available here - https://docs.djangoproject.com/en/1.2/releases/1.2.4/
Before any upgrade, you should make a backup of your existing Django applications and databases.
To upgrade the application, go to the Control Panel > System tab (if necessary, click on Select Another System (Subscription) and choose the correct subscription) > Applications > Django. Click on the name of the application, and then on Upgrade To Latest.
