PaygateDeveloper documentation
422invalid_transitionplatform

That state transition is not allowed

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

The object's current state has no edge to the state you asked for.

Why the API refuses

the requested state transition is not allowed

What to do

Read the object and branch on its actual status rather than on what you expected it to be by now. The state machine for each entity is on its schema page in the reference.