Doing multipart requests with PowerShell is quite complicated and requires several extra steps for large file uploads. An easy example for a small file can be found on StackOverflow. An in depth discussion can be found in this blog post.

It would be a huge improvement if the WebRequestPSCmdlets (Invoke-RestMethod and Invoke-WebRequest) could be enhanced so that they support Multipart messages directly.

For an implementation I would expect the following parameters:

• MultipartFile (Path)
• MultipartName (Name to be used in Multipart message)

.NET Core seems to have support for MultipartContent which may simplify the implementation.