Cannot convert from system.datetime to long in ASP.NET core 3

<pre><big><pre>First in the database for time, I chose Big Int, but then I changed it to Small Data Time.

public async Task<IActionResult> Create(int? id, int? type)
{
    if (id == null || type == null)
    {
        return NotFound();
    }

    InsuranceViewModel model = null;
    ViewBag.Type = type;

    var companies = await _context.InsuranceCompany
        .Where(e => e.IsActice)
        .ToListAsync();
    ViewData["CompanyList"] = new SelectList(companies, "Id", "CompanyName");

    if ((InsuranceType)type == InsuranceType.Body)
    {
        var lastBody = _context.BodyInsurance
                       .Where(e => e.VehicleInformationId == id.Value)
                       .AsEnumerable()
                       .LastOrDefault();

        model = new InsuranceViewModel
        {
            InsuranceType = InsuranceType.Body,
            InsuranceNumber = "",
            IssueDate = lastBody != null
                ? new DateTime(lastBody.ExpireDate).AddDays(1)
                : DateTime.Today,
            ExpireDate = lastBody != null
                ? new DateTime(lastBody.ExpireDate).AddYears(1)
                : DateTime.Today.AddYears(1),
            VehicleInformationId = id.Value
        };
    }
    else if ((InsuranceType)type == InsuranceType.Thirdpart)
    {
        var lastThirdParty = _context.ThirdPartyInsurance
                             .Where(e => e.VehicleInformationId == id.Value)
                             .AsEnumerable()
                             .LastOrDefault();

        var thirdParty = await _context.ThirdPartyInsurance
        .Include(e => e.InsuranceCompany)
        .FirstOrDefaultAsync(e => e.Id == id.Value);

        model = new InsuranceViewModel
        {
            InsuranceType = InsuranceType.Thirdpart,
            InsuranceNumber  = "",
            IssueDate = lastThirdParty != null
                ? new DateTime(lastThirdParty.ExpireDate).AddDays(1)
                : DateTime.Today.Ticks,
            ExpireDate = lastThirdParty != null
                ? new DateTime(lastThirdParty.ExpireDate).AddYears(1)
                : DateTime.Today.AddYears(1),
            VehicleInformationId = id.Value
        };
    }

    return View(model);
}

var lastThirdParty = await _context.ThirdPartyInsurance.Include(e => e.InsuranceCompany)
    .Where(e => e.VehicleInformationId == id)
    .OrderBy(e => e.ExpireDate)
    .LastOrDefaultAsync();

var lastBody = await _context.BodyInsurance.Include(e => e.InsuranceCompany)
    .Where(e => e.VehicleInformationId == id)
    .OrderBy(e => e.ExpireDate)
    .LastOrDefaultAsync();

The error is on this line:
? new DateTime(lastBody.ExpireDate).AddDays(1)
lastBody.ExpireDate ----- cannot convert from system.datetime to long