C++ getting an error when uploading file

zangetsu The file metadata shouldn't cause an issue like this. I do see that you're getting two different HTTP responses though, one with a 200 status code (for the successful file upload), and then one with a 400 status code (which can occur when the servers receive an invalid HTTP request). So, as Здравко indicated, it looks like you may actually be sending more than one HTTP request, perhaps one valid one for the upload call and then one invalid one. (For instance, you might be sending additional data on the connection, after the actual API call data is sent.)