MultipartException: Current request is not a multipart request

It looks like the problem is request to server is not a multi-part request. Basically you need to modify your client-side form. For example:

<form action="..." method="post" enctype="multipart/form-data">
  <input type="file" name="file" />
</form>

Hope this helps.

When you are using Postman for multipart request then don't specify a custom Content-Type in Header. So your Header tab in Postman should be empty. Postman will determine form-data boundary. In Body tab of Postman you should select form-data and select file type. You can find related discussion at https://github.com/postmanlabs/postman-app-support/issues/576