Bad Request (400) when posting IFormFile

Question

I have a .NET Core API project that has a simple endpoint to upload a file:

[Route("api/[controller]")]
[ApiController]
public class FilesController : Controller
{
    private IFilesService _filesService { get; set; }

    public FilesController(IFilesService filesService)
    {
        _filesService = filesService;
    }

    [HttpPost]
    public async Task<IActionResult> UploadFile(IFormFile file)
    {
        var model = await _filesService.UploadFile(file);
        return Ok();
    }
}

I've tried to test this using Postman, but each time I post a file to the endpoint, I get a 400 Bad Request error. My endpoint never gets hit.

I have several other POST endpoints that work just fine, so it's an issue either with this specific endpoint or with Postman. Here is my setup in Postman:

I've been spinning my wheels trying to figure out what the issue is, but there's not much to this at all, and I'm following examples I've seen online.

What am I doing wrong?

Answer 1

I see you have set the [ApiController] attribute so I'm assuming that you are running ASP.Net Core 2.1.

If it's not set already, try modifying services.AddMvc() to services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1); in Startup.cs.

I had a similar issue a while back and the above change fixed it for me. I found the answer to my problem here.

Hope this helps!