Upload using RESTful API

I'm trying to write a python script to upload a file to the vault using the RESTful API in 11SP12. Here is the doc specific to the upload operation: The vault.UploadFile Method uploads the file chunk within a given transaction. The File ID is generated on the client and passed to the vault server using the fileId query option. Here is a sample HTTP post from the doc: POST vault/.../vault.UploadFile Content-Type: application/octet-stream Content-Length: 37410 transactionid: 8970e933322d1328537f645d3683214c … file chunk content When I try to upload, my POST looks pretty much identical to this since I first start a transaction to the the transaction ID and then do the upload. For the fileId, I am generating a MD5 hash of the file's content. However, when I execute the upload operation, I get the following error: {'error': {'code': '500', 'message': "Can't bind model."}} I've tried tweaking a number of things in my request, but I always get the same error. Aras support suggested I include Content-Disposition and Content-Range headers in my request, but I get the same result. Here's a an example POST from my script: POST localhost/.../vault.UploadFile HTTP/1.1 Host: localhost User-Agent: python-requests/2.18.3 Accept-Encoding: gzip, deflate Accept: */* Connection: keep-alive DATABASE: InnovatorSolutions LOCALE: en-US TIMEZONE_NAME: Eastern Standard Time AUTHUSER: admin AUTHPASSWORD: 607920b64fe136f9ab2389e371852af2 transactionId: 4f1006553c262ee2a05b4ce3de57948a Content-Type: application/octet-stream Content-Disposition: attachment; filename="test-data.txt" Content-Range: bytes 0-45/45 Transfer-Encoding: chunked 2d This data is test data that I need to test. 0 Has anyone tried this out and got it working?