i need to receive an async notification from alipay, which will POST to my api endpoint: https://my-domain.vercel.app/api/alipay/notify/ . it fails. after i contacted alipay's support, they told me that the POST request got http status 0 error returned from my app which is deployed on Vercel. since http 0 is an init error, i can't find any clues to correct it. can someone help me on this?

i can connect to the endpoint correctly with postman remotely. from alipay support, the notifications have been sent but in vercel's log, no requests were seen. but since alipay told me it was http 0 error, i suppose it was normal that no requests were forwarded to my app at all, so no logs. Does any one have any suggestions on this issue?

thanks.