The SxcApiController was the old base class for WebApi Controllers in 2sxc up to 10.25. Now you should use the new ApiController. 

1. Change to inherit from ToSic.Sxc.Dnn.ApiController
   So change public class YourController: SxcApiController to 
   public class YourController: ToSic.Sxc.Dnn.ApiController
2. Change any AsDynamic(someList) to AsList(someList)
3. If you were using Serializer.Prepare(someList) now use DataToDictionary(Edit.Enabled).Convert(someList) instead
4. Follow the other recommendations in the RazorComponent recipe