My team has an outstanding defect where we try to close/void a PayPal order many times. Previously any extra/duplicate void request would result in an error with an API error code -- we'd ignore it and move on. Starting October 31st, those duplicate void requests are returning an HTTP 400 status code. Is anyone else experiencing this? So far PayPal support has been slow to respond.
(Obviously we are also working on resolving the defect so we only void once, but in the mean time there is a lot of manual clean up to do).
I've been able to reproduce this in the sandbox environment so perhaps it's expected behavior? The SOAP API is legacy so I wouldn't expect changes like this.
I'd go with it being the now-expected behavior. Legacy APIs haven't per se changed, but services fulfilling requests behind the scenes definitely have. By now you can essentially think of legacy APIs as a "compatibility layer" or interface over a much more modern stack of software services than what existed back when those legacy APIs were originally created.