On my MVC Web Api Put what may be causing an Internal Server Error: 500

I am somewhat new to working with MVC Web Api and I was excited to get my MVC Web Api GET to work, but really frustrated trying to formulate my Web Api Put

I tried to create my dataset to be identical to the the but I did add one property, could that be an issue? Also, I noticed that some of my values on my checkboxes and such are returning nulls these are set up in the model as boolean, so I don't know.

Here is my Web Api put

// PUT: api/Datasets/5
        [ResponseType(typeof(void))]
        public async Task<IHttpActionResult> PutDataset(int id, Dataset dataset)
        {
            if (!ModelState.IsValid)
            {
                return BadRequest(ModelState);
            }

            if (id != dataset.Dataset_ID)
            {
                return BadRequest();
            }

            db.Entry(dataset).State = EntityState.Modified;

            try
            {
                await db.SaveChangesAsync();
            }
            catch (DbUpdateConcurrencyException)
            {
                if (!DatasetExists(id))
                {
                    return NotFound();
                }
                else
                {
                    throw;
                }
            }

            return StatusCode(HttpStatusCode.NoContent);
        }

Here is my HttpPost from my form with my datamodel

[HttpPost]

 public ActionResult TestDataset(Dataset dataset)
    {
        using (var client = new HttpClient())
        {
        
        client.BaseAddress = new Uri("http://localhost:4251/");

        //HTTP POST
        
        var postTask = client.PostAsJsonAsync<Dataset>("api/datasets/1", dataset);
        postTask.Wait();

        var result = postTask.Result;
        if (result.IsSuccessStatusCode)
        {
            return RedirectToAction("Index");
        }
    }

    ModelState.AddModelError(string.Empty, "Server Error. Please contact administrator.");

    return View(dataset);
}

This is my dataset.cs created from Entity Framework on my Web Api Project

public partial class Dataset
    {
        [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2214:DoNotCallOverridableMethodsInConstructors")]
        public Dataset()
        {
            this.Attachment = new HashSet<Attachment>();
            this.Contact = new HashSet<Contact>();
            this.Location1 = new HashSet<Location>();
        }
    
        public int Dataset_ID { get; set; }
        public int Category_ID { get; set; }
        public string Provider { get; set; }
        public string Name { get; set; }
        public string Institution { get; set; }
        public string Description { get; set; }
        public string Location { get; set; }
        public Nullable<bool> Domestic { get; set; }
        public Nullable<bool> International { get; set; }
        public Nullable<bool> Includes_PHI { get; set; }
        public Nullable<bool> PHI_Limited { get; set; }
        public Nullable<bool> Includes_PIL { get; set; }
        public Nullable<bool> PIL_Limited { get; set; }
        public Nullable<bool> Citation_Requirements { get; set; }
        public string Citation_Comments { get; set; }
        public Nullable<System.DateTime> Availability_Beg_DT { get; set; }
        public Nullable<System.DateTime> Availability_End_DT { get; set; }
        public Nullable<bool> Subscription_Renewal { get; set; }
        public Nullable<System.DateTime> Subscription_Renewal_DT { get; set; }
        public Nullable<bool> Retention_Expiry { get; set; }
        public Nullable<System.DateTime> Retention_Expiry_DT { get; set; }
        public Nullable<bool> Data_Destruction { get; set; }
        public Nullable<System.DateTime> Data_Destruction_DT { get; set; }
        public string Data_Destruction_Instructions { get; set; }
        public Nullable<int> Contract_ID { get; set; }
        public bool Draft_Status { get; set; }
        public bool Admin_Only { get; set; }
        public string Dataset_Alias { get; set; }
        public Nullable<bool> Loc_Amazon { get; set; }
        public Nullable<bool> Loc_IT_Research { get; set; }
        public Nullable<bool> Loc_Research_Proj { get; set; }
        public Nullable<bool> Loc_Secure_Data { get; set; }
        public Nullable<bool> Loc_Mercury { get; set; }
        public Nullable<bool> Loc_Research_CC { get; set; }
        public Nullable<bool> Loc_Research_VM { get; set; }
        public Nullable<bool> Loc_External { get; set; }
        public Nullable<bool> Access_Url { get; set; }
        public Nullable<bool> Access_Download_App { get; set; }
        public Nullable<bool> Access_Lab_Terminal { get; set; }
        public Nullable<bool> Access_Email_Req { get; set; }
        public Nullable<bool> Access_File_Download { get; set; }
        public Nullable<bool> Access_Other { get; set; }
        public string Location_Notes { get; set; }
        public string Access_Notes { get; set; }
        public Nullable<System.DateTime> Date_Added { get; set; }
        public Nullable<System.DateTime> Date_Modified { get; set; }
        public string Added_By_User { get; set; }
        public string Updated_By_User { get; set; }
        public Nullable<bool> External_Collaborators { get; set; }
    
        [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2227:CollectionPropertiesShouldBeReadOnly")]
        public virtual ICollection<Attachment> Attachment { get; set; }
        public virtual Category Category { get; set; }
        [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2227:CollectionPropertiesShouldBeReadOnly")]
        public virtual ICollection<Contact> Contact { get; set; }
        public virtual Contract Contract { get; set; }
        [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2227:CollectionPropertiesShouldBeReadOnly")]
        public virtual ICollection<Location> Location1 { get; set; }
    }

this is the model I am returning:

 public class Dataset
    {
        public int Dataset_ID { get; set; }
        public int Category_ID { get; set; }
        public string Provider { get; set; }
        public string Name { get; set; }
        public string Institution { get; set; }
        public string Description { get; set; }
        public string Location { get; set; }
        public Nullable<bool> Domestic { get; set; }
        public Nullable<bool> International { get; set; }
        public Nullable<bool> Includes_PHI { get; set; }
        public Nullable<bool> PHI_Limited { get; set; }
        public Nullable<bool> Includes_PIL { get; set; }
        public Nullable<bool> PIL_Limited { get; set; }

       
        public Nullable<bool> Citation_Requirements { get; set; }
        public string Citation_Comments { get; set; }
        public Nullable<System.DateTime> Availability_Beg_DT { get; set; }
        public Nullable<System.DateTime> Availability_End_DT { get; set; }
        public Nullable<bool> Subscription_Renewal { get; set; }
        public Nullable<System.DateTime> Subscription_Renewal_DT { get; set; }
        public Nullable<bool> Retention_Expiry { get; set; }
        public Nullable<System.DateTime> Retention_Expiry_DT { get; set; }
        public Nullable<bool> Data_Destruction { get; set; }
        public Nullable<System.DateTime> Data_Destruction_DT { get; set; }
        public string Data_Destruction_Instructions { get; set; }
        public Nullable<int> Contract_ID { get; set; }
        public bool Draft_Status { get; set; }
        public bool Admin_Only { get; set; }
        public string Dataset_Alias { get; set; }
        public Nullable<bool> Loc_Amazon { get; set; }
        public Nullable<bool> Loc_IT_Research { get; set; }
        public Nullable<bool> Loc_Research_Proj { get; set; }
        public Nullable<bool> Loc_Secure_Data { get; set; }
        public Nullable<bool> Loc_Mercury { get; set; }
        public Nullable<bool> Loc_Research_CC { get; set; }
        public Nullable<bool> Loc_Research_VM { get; set; }
        public Nullable<bool> Loc_External { get; set; }
        public Nullable<bool> Access_Url { get; set; }
        public Nullable<bool> Access_Download_App { get; set; }
        public Nullable<bool> Access_Lab_Terminal { get; set; }
        public Nullable<bool> Access_Email_Req { get; set; }
        public Nullable<bool> Access_File_Download { get; set; }
        public Nullable<bool> Access_Other { get; set; }
        public string Location_Notes { get; set; }
        public string Access_Notes { get; set; }
        public Nullable<System.DateTime> Date_Added { get; set; }
        public Nullable<System.DateTime> Date_Modified { get; set; }
        public string Added_By_User { get; set; }
        public string Updated_By_User { get; set; }
        public Nullable<bool> External_Collaborator { get; set; }

        public ICollection<Attachment> Attachment { get; set; }
        public ICollection<Contact> Contact { get; set; }

        public ICollection<Category> Categories { get; set; }

        public IEnumerable<SelectListItem> CategoryList { get; set; }
    }