Since Automation Platform SDK V3.5.16.0 comes along with a completely refactored Core interface and a set of newly created interfaces. AddOns which are built against AP SDK V3.5.16.0 and later can not be installed into CODESYS version less than V3.5.16.0 by default.

The attached document describes the prerequisites and limitations for compatibility handling along with the two necessary packages CODESYS Package Manager and CODESYS Compatibility Package.