Request:

curl --request POST
--url https://api.bitbucket.org/2.0/repositories/owner/slug/hooks
--header 'authorization: Basic 123456789'
--header 'cache-control: no-cache'
-header 'content-type: multipart/form-data; boundary=--011000010111000001101001'
--form 'description=Webhook description'
--form url=path_to_yrl
--form active=true
--form events=repo:push

Response:

{"error": {"message": "You cannot access body after reading from request's data stream", "id": "0b76372bbec44767bbeb5b06d80cc256"}}

I simply can't create a webhook via API. I can read webhooks with no problem. At first I was using PHP to call the api and then I move to various POST apps from Chrome store to eliminate mistakes on my part.