It’s been a while since we announced the retirement of the API version 3 (API v3). From now on this old version of the API is no longer available. If you haven’t done so yet, please upgrade to API version 4 (API v4). The upgrade guide can help you transition from using API v3 to API v4.
While preparing the retirement of this old API version we have communicated with customers still using it, making you aware of the fact and trying to answer questions. Should you still use API v3 and have problems in upgrading to API v4, please contact Support.