I get the following error when i run my update form. but can't track down the accrual problem. ASP.NET C#

Error:
Additional information: An error occurred while updating the entries. See the inner exception for details.

Happens on the save changes()

System.Data.Entity.Infrastructure.DbUpdateException was unhandled by user code
  HResult=-2146233087
  Message=An error occurred while updating the entries. See the inner exception for details.
  Source=EntityFramework
  StackTrace:
       at System.Data.Entity.Internal.InternalContext.SaveChanges()
       at System.Data.Entity.Internal.LazyInternalContext.SaveChanges()
       at System.Data.Entity.DbContext.SaveChanges()
       at EPI2016r1.Controllers.HomeController.prRegistration(FormCollection fc) in c:\LearnMVCsites\EPI2016r1\EPI2016r1\Controllers\HomeController.cs:line 266
       at lambda_method(Closure , ControllerBase , Object[] )
       at System.Web.Mvc.ActionMethodDispatcher.Execute(ControllerBase controller, Object[] parameters)
       at System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext, IDictionary`2 parameters)
       at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary`2 parameters)
       at System.Web.Mvc.Async.AsyncControllerActionInvoker.ActionInvocation.InvokeSynchronousActionMethod()
       at System.Web.Mvc.Async.AsyncControllerActionInvoker.<BeginInvokeSynchronousActionMethod>b__39(IAsyncResult asyncResult, ActionInvocation innerInvokeState)
       at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResult`2.CallEndDelegate(IAsyncResult asyncResult)
       at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResultBase`1.End()
       at System.Web.Mvc.Async.AsyncResultWrapper.End[TResult](IAsyncResult asyncResult, Object tag)
       at System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethod(IAsyncResult asyncResult)
       at System.Web.Mvc.Async.AsyncControllerActionInvoker.AsyncInvocationWithFilters.<InvokeActionMethodFilterAsynchronouslyRecursive>b__3d()
       at System.Web.Mvc.Async.AsyncControllerActionInvoker.AsyncInvocationWithFilters.<>c__DisplayClass46.<InvokeActionMethodFilterAsynchronouslyRecursive>b__3f()
  InnerException: System.Data.Entity.Core.UpdateException
       HResult=-2146233087
       Message=An error occurred while updating the entries. See the inner exception for details.
       Source=EntityFramework
       StackTrace:
            at System.Data.Entity.Core.Mapping.Update.Internal.UpdateTranslator.Update()

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