The Sandbox API is currently in major version 3.4.0. We only release a new version when backward compatibility is not feasible for the APIs. This is to prevent breakages for existing developers. However, there features that remain backward compatible.
Features that we consider to be backward compatible are:
Adding new API resources.
Adding new 'required' input params to existing API methods.
Adding new attributes to existing API responses.
Changing the order of attributes in existing API responses.
Changing the length or format of objects
Important to note: you can then continue to use the old API version, or update your application to the new Sandbox API version.
All requests use the default setting unless you override the API version. By specifying a version in a REST request, you can get expected responses regardless of future changes to the API. You can also manually set the
X-Api-Version header to use a specific version for a given API request.
Sandbox will communicate the creation of any new version as well as any deprecation of older versions