Unfortunately, support for Unity 2017 has been dropped since NodeCanvas v3. There are c# language features that are now being used that are not supported in any version before 2018.4. Furthermore, there is a specific workflow in regards to Unity nested prefabs as well and I didn’t want to maintain multiple code paths (using directives) any longer since it becomes much harder as well as prone to errors. Cant you update your project to 2018.4 ?
Gavalakis
