Server Error in '/' Application.

Value cannot be null.
Parameter name: input

 Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.ArgumentNullException: Value cannot be null.
Parameter name: input

Source Error:

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace:

 
 [ArgumentNullException: Value cannot be null.
 Parameter name: input]
 System.Text.RegularExpressions.Regex.IsMatch(String input) +81
 Kol1.Web.Models.Leg.MobileFilter.IsMobile() in c:\menahem\Sites\Kol1Win7Solution\Kol1.Web\Models\Leg\MobileFilter.cs:18
 Kol1.Web.Models.Leg.MobileFilter.OnResultExecuting(ResultExecutingContext filterContext) in c:\menahem\Sites\Kol1Win7Solution\Kol1.Web\Models\Leg\MobileFilter.cs:25
 System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilter(IResultFilter filter, ResultExecutingContext preContext, Func`1 continuation) +41
 System.Web.Mvc.<>c__DisplayClass1c.<InvokeActionResultWithFilters>b__19() +22
 System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilter(IResultFilter filter, ResultExecutingContext preContext, Func`1 continuation) +245
 System.Web.Mvc.<>c__DisplayClass1c.<InvokeActionResultWithFilters>b__19() +22
 System.Web.Mvc.ControllerActionInvoker.InvokeActionResultWithFilters(ControllerContext controllerContext, IList`1 filters, ActionResult actionResult) +176
 System.Web.Mvc.Async.<>c__DisplayClass2a.<BeginInvokeAction>b__20() +88
 System.Web.Mvc.Async.<>c__DisplayClass25.<BeginInvokeAction>b__22(IAsyncResult asyncResult) +102
 System.Web.Mvc.Async.WrappedAsyncResult`1.End() +50
 System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeAction(IAsyncResult asyncResult) +42
 System.Web.Mvc.<>c__DisplayClass1d.<BeginExecuteCore>b__18(IAsyncResult asyncResult) +14
 System.Web.Mvc.Async.<>c__DisplayClass4.<MakeVoidDelegate>b__3(IAsyncResult ar) +16
 System.Web.Mvc.Async.WrappedAsyncResult`1.End() +50
 System.Web.Mvc.Controller.EndExecuteCore(IAsyncResult asyncResult) +55
 System.Web.Mvc.Async.<>c__DisplayClass4.<MakeVoidDelegate>b__3(IAsyncResult ar) +16
 System.Web.Mvc.Async.WrappedAsyncResult`1.End() +50
 System.Web.Mvc.Controller.EndExecute(IAsyncResult asyncResult) +45
 System.Web.Mvc.Controller.System.Web.Mvc.Async.IAsyncController.EndExecute(IAsyncResult asyncResult) +10
 System.Web.Mvc.<>c__DisplayClass8.<BeginProcessRequest>b__3(IAsyncResult asyncResult) +25
 System.Web.Mvc.Async.<>c__DisplayClass4.<MakeVoidDelegate>b__3(IAsyncResult ar) +16
 System.Web.Mvc.Async.WrappedAsyncResult`1.End() +50
 System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult) +45
 System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.EndProcessRequest(IAsyncResult result) +9
 System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +577
 System.Web.HttpApplication.ExecuteStepImpl(IExecutionStep step) +132
 System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +163

Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.8.4682.0