asp.net – IDENTITY_INSERT设置为关闭错误

“当IDENTITY_INSERT设置为OFF时,无法在表”TABLE_NAME“中插入标识列的显式值.

我不知道为什么这个问题出现,我将主键设置为身份,它也被设置为在Visual Studio表设计器中自动递增.有什么办法可以调整Visual Studio中的表设计器中的IDENTITY_INSERT参数？或者还有一些其他可能导致此问题.

更新：@Brian – 据我所知,我没有明确设置值,这里是添加到表的代码.

//Add viewer
public void addViewer(ModelStateDictionary modelState,Users user)
{
   var userToAdd = new UserRoles();
   userToAdd.Users = user;

   if (String.IsNullOrEmpty(userToAdd.Users.Username))
   {
      modelState.AddModelError("noName","Please enter a username for the new Viewer");
   }

   //See if Committee Member already exists
   try
   {
      userToAdd = _db.UserRoles.First(ur => ur.Users.Username == userToAdd.Users.Username);
      modelState.AddModelError("userExists","A Viewer with that username already exists in the system");
      return;
    }
    catch (Exception e)
    {
       if (modelState.IsValid)
       {
          //Assign Committee Member role
          userToAdd.Role = "Viewer";
          userToAdd.Users = user;
          //Add new Committee Member to User Roles and associated username to Users
          _db.AddToUserRoles(userToAdd);
          _db.SaveChanges();
       }
    }
}