• Existing C++ plugins must be adapted and re-compiled for R21.
• Building C++ plugins will require Visual Studio 2017 or Xcode 10.
• Only one version of Cinema 4D will exist in the future.
• A new licensing system replaces the old, serial number based system. Plugins, that base their licensing scheme on that serial number, must adapt.
• Also, the SNHookClass plugin type has been removed.

More information on Cinema 4D R21 is found here:

• Cinema 4D R21 Overview
• Complete Feature List
• Cinema 4D R21 FAQ

The adapted C++ and Python SDKs will be published with the release of Cinema 4D R21 in September.