API Polymorphism was added in 2sxc 9.35 and allows you to have APIs in subfolders, like

/staging/api/FormController.cs

instead of 

/api/FormController.cs

To make an app backwards compatible, simply do this:

  1. move the files up one folder, so they are in a root api folder
  2. adjust the JavaScript files to call this endpoint, without the additional word (usually staging or live)