I have tested the v2 REST call and it returns the success status. However the attachment (a zip archive) is silently discarded. Sending an equivalent request with a plain text file works as expected. Are the any problems while uploading binary files through the API proxy?
I'm not very fond of using API v2 as it is marked 'Open Beta' according to the v2 developer documentation.
Using REST v1 returns the error mentioned in my first message.
I did more tests with binary attachments. It seems that the last binary attachment is not correctly recognized / discarded. The API should at least reject the whole request if the number of attachments in the "api.request" JSON differs from the received files.
