System.FormatException HResult=0x80131537 Message=String was not recognized as a valid DateTime. Source=mscorlib StackTrace: at System.DateTimeParse.ParseExact(String s, String format, DateTimeFormatInfo dtfi, DateTimeStyles style) at System.DateTime.ParseExact(String s, String format, IFormatProvider provider) at BarcodeCreation.Controllers.MondayMeetingReportController.FetchRow1() in E:\BACKUP_Barcode\working\BarcodeCreation\BarcodeCreation\Controllers\MondayMeetingReportController.cs:line 18325 at BarcodeCreation.Controllers.WeeklyTopstyleController.Report() in E:\BACKUP_Barcode\working\BarcodeCreation\BarcodeCreation\Controllers\WeeklyTopstyleController.cs:line 37 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.<>c__DisplayClass42.b__41() at System.Web.Mvc.Async.AsyncResultWrapper.<>c__DisplayClass8`1.b__7(IAsyncResult _) at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResult`1.End() at System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethod(IAsyncResult asyncResult) at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c__DisplayClass37.<>c__DisplayClass39.b__33() at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c__DisplayClass4f.b__49()

if you are facing this issue suddenly but code was working before so please check you computer date format. if your computer date format has changed so might be you will face this kind of issue. https://www.windowscentral.com/how-change-date-and-time-formats-windows-10