PaygateDeveloper documentation
400api.unknown_versionapi

Unknown API version

Returned by the implementation; no specification rule declares it yet.

The PG-Version header names a version that does not exist or is not served. The detail lists the versions that are.

Why the API refuses

unknown API version; supported versions:

What to do

Pin a dated version you have tested against and change it deliberately — see the changelog for what each one changed. Omitting the header is also fine: you get the default. What you should not do is send a version string built at runtime from today's date.