ASP.NET Core Web API & Entity Framework Core: physical storage not working on production server

Question

I have an ASP.NET Core Web API where an endpoint uploads a PDF file. The current method to upload to physical storage (the hard disk) is this:

[HttpPost]
public async Task<ActionResult> Upload([FromForm] UploadModel uploadModel)
{
    var fileName = System.IO.Path.Combine(_environment.ContentRootPath,
                                          "uploads", 
                                          uploadModel.ImeiOrSerial + "" + uploadModel.EquipmentInvoice.FileName);

    await uploadModel.EquipmentInvoice.CopyToAsync(
            new System.IO.FileStream(fileName, System.IO.FileMode.Create));

    using (var context = _context)
    {
         var equipment = new Equipment();

         equipment.TypeOfEquipment = uploadModel.TypeOfEquipment;
         equipment.EquipmentBrand = uploadModel.EquipmentBrand;
         equipment.ModelOrReference = uploadModel.ModelOrReference;
         equipment.ImeiOrSerial = uploadModel.ImeiOrSerial;

         equipment.Path = uploadModel.ImeiOrSerial + "" + uploadModel.EquipmentInvoice.FileName;

         _context.Equipment.Add(equipment);

         await _context.SaveChangesAsync();

         return Ok(await _context.Equipment.FindAsync(equipment.IdEquipment));
     }
}

If I do this in development, everything works perfectly, I get the name of the PDF invoice and it gets in the uploads file inside the solution directory

But if try to do this on my IIS web server, it doesn't work.

I enabled swagger in production mode to see what error the swagger was throwing, but I only get this:

I have no clue what I'm doing wrong.

UPDATE

I wrap my post method in a try catch and now it shows me the following error:

Answer 1

Ady's comment is correct. By default, the uploads will not included in publish. You need enable it in your .csproj file. You can check the doc about Visual Studio publish profiles (.pubxml) for ASP.NET Core app deployment.

You can add below code to your .csproj file.

<ItemGroup> 
  <Content Include="uploads\**"> 
    <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory> 
  </Content> 
</ItemGroup>

If your uploads folder is empty, you can create a simple txt file in it or use MakeDir to create it when publish.

Answer 2

This is what I found that work for me, do the following:

Go to the IIS manager.

Right click on your backend page, in my case its called API:

Then go to Edit Permissions:

Select the option that says IIS_IUSRS, like shown in the previous image, then click in the edit button.

Pick again the option that says IIS_IUSRS and give permission to full control and modify.

Finally go to the wwwroot folder where you published your API and create a new folder where its gonna be located all the files. In my case I named the file "uploads"

And that's it, you should be able to upload files, and locate them in physical storage