unsupported_version
Status 404. That API version is not served here.
What it means
The version in the address is not one this platform serves. supported_versions lists the ones that are.
What to do
Use one of them: the version is the part of the address right after /api.
Safe to send again?
Not as it is. Change what the answer points to, then send the request.
What else the answer carries
supported_versions: The versions this platform serves.
Every code, and the shape of an error answer: Errors.