strategy_not_allowed

HTTP 422. The strategy is not valid for this end-user’s market (e.g. a spot strategy on a futures account), or is not supported on this surface.

What to do: Check the strategy’s spot/leverage support against the end-user’s exchange.

Every error is an RFC 9457 problem document - match on code (stable forever), show detail to humans, and quote instance when reporting an occurrence to support.