[SOLVED] How do I do file upload using ASP.NET Core 6 minimal api?


I want to create a simple file upload endpoint in ASP.NET Core 6 and thought it would be as easy as described here https://dotnetthoughts.net/handling-file-uploads-in-openapi-with-aspnet-core/.

When I have an endpoint defined like:

app.MapPost("/upload", (IFormFile file) =>
    //Do something with the file
    return Results.Ok();

I get a 415 back when I call the endpoint. The message I get back is something like:

Expected a supported JSON media type but got "multipart/form-data; …

Not sure why it expected a supported json when I say that the endpoint should accept multipart/form-data.

Any ideas or thoughts on what to do here?


Currently out of the box support for binding in Minimal APIs is quite limited. Supported binding sources:

  • Route values
  • Query string
  • Header
  • Body (as JSON)
  • Services provided by dependency injection
  • Custom

NOTE: Binding from forms is not natively supported in .NET 6

You can either leverage custom binding or use special types handling:

app.MapPost("/upload", (HttpRequest request) =>
    //Do something with the file
    var files = request.Form.Files;
    return Results.Ok();

Answered By – Guru Stron

Answer Checked By – Marie Seifert (BugsFixing Admin)

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