How to solve the error in file upload code C#?

I am trying to upload images to the server and save them so that I can use them on user site but I am getting this mapping error and need help to solve this.

I tried changing the property name from string to IFormFile but that didn't work. Then I changed it again to string and created another property

public IFormFile Thumbnail 

but I get an ambiguity error to solve this I changed the property to

public IFormFile Thumbnailimg 

and same for the Bug and ShortVideo.

Model.cs

using Microsoft.AspNetCore.Http;
using System;
using System.Collections.Generic;

namespace BuildShow.Models
{
    public partial class Assets
    {
        public int Id { get; set; }
        public int TypeFid { get; set; }
        public int CategoryFid { get; set; }
        public string Name { get; set; }
        public string Title { get; set; }
        public string ShortDescription { get; set; }
        public string LongDescription { get; set; }
        public string ArticleText { get; set; }
        public string Thumbnail { get; set; }
        public string Hero { get; set; }
        public string Bug { get; set; }
        public string ShortVideo { get; set; }
        public string VideoId { get; set; }
        public int TagFid { get; set; }
        public int ContributerFid { get; set; }
        public bool? Enabled { get; set; }
        public bool? Featured { get; set; }
        public bool? ShowOnHomePage { get; set; }
        public string SortOrder { get; set; }

        public virtual Categories CategoryF { get; set; }
        public virtual Contributor ContributerF { get; set; }
        public virtual Tags TagF { get; set; }
        public virtual AssetType TypeF { get; set; }


        public IFormFile Thumbnailimg { get; set; }
        public IFormFile Heroimg { get; set; }
        public IFormFile Bugimg { get; set; }
        public IFormFile ShortVideoup { get; set; }
    }
}

Controller.cs

if (id != assets.Id)
{
    return NotFound();
}

if (ModelState.IsValid)
{
    try
    {
        _context.Update(assets);
        await _context.SaveChangesAsync();
    }
    catch (DbUpdateConcurrencyException)
    {
        if (!AssetsExists(assets.Id))
        {
            return NotFound();
        }
        else
        {
            throw;
        }
    }

    return RedirectToAction(nameof(Index));
}

Error:

InvalidOperationException: The property 'Assets.Thumbnailimg' is of an interface type ('IFormFile'). If it is a navigation property manually configure the relationship for this property by casting it to a mapped entity type, otherwise ignore the property using the NotMappedAttribute or 'EntityTypeBuilder.Ignore' in 'OnModelCreating'.