Thank you for sharing this finding with us. I confirm the error reproduces with the provided steps. Here is what the browser shows when you select the Reports tab from the Report Server Manager after changing the Mail Template configuration:
Server Error in '/' Application.
Cannot perform runtime binding on a null reference
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: Microsoft.CSharp.RuntimeBinder.RuntimeBinderException: Cannot perform runtime binding on a null reference
Source Error:
Line 77: isNew : function() { return true; },
Line 78: LocalUsersMailTemplate: {
Line 79: Subject: "@Html.Raw(Model.DefaultLocalUsersMailTemplate.Subject.Replace("\\", "\\\\").Replace("\"", "\\\""))",
Line 80: Body: "@Html.Raw(Model.DefaultLocalUsersMailTemplate.Body.Replace("\\", "\\\\").Replace("\"", "\\\""))"
Line 81: },
Source File: c:\Program Files (x86)\Progress\Telerik Report Server\Telerik.ReportServer.Web\Views\Report\Scheduling.cshtml Line: 79
Stack Trace:
[RuntimeBinderException: Cannot perform runtime binding on a null reference]
CallSite.Target(Closure , CallSite , Object , String , String ) +230
System.Dynamic.UpdateDelegates.UpdateAndExecute3(CallSite site, T0 arg0, T1 arg1, T2 arg2) +742
ASP._Page_Views_Report_Scheduling_cshtml.Execute() in c:\Program Files (x86)\Progress\Telerik Report Server\Telerik.ReportServer.Web\Views\Report\Scheduling.cshtml:79
System.Web.WebPages.WebPageBase.ExecutePageHierarchy() +252
System.Web.Mvc.WebViewPage.ExecutePageHierarchy() +148
System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage) +122
System.Web.Mvc.Html.PartialExtensions.Partial(HtmlHelper htmlHelper, String partialViewName, Object model, ViewDataDictionary viewData) +136
ASP._Page_Views_Report_Index_cshtml.<Execute>b__20(TextWriter __razor_template_writer) in c:\Program Files (x86)\Progress\Telerik Report Server\Telerik.ReportServer.Web\Views\Report\Index.cshtml:317
Kendo.Mvc.UI.HtmlElement.WriteTo(TextWriter output) +169
Kendo.Mvc.Extensions.EnumerableExtensions.Each(IEnumerable`1 instance, Action`1 action) +159
Kendo.Mvc.UI.HtmlElement.WriteTo(TextWriter output) +266
Kendo.Mvc.Extensions.EnumerableExtensions.Each(IEnumerable`1 instance, Action`1 action) +159
Kendo.Mvc.UI.HtmlElement.WriteTo(TextWriter output) +266
Kendo.Mvc.UI.TabStrip.WriteHtml(HtmlTextWriter writer) +359
Kendo.Mvc.UI.WidgetBase.ToHtmlString() +117
System.Web.WebPages.WebPageBase.Write(Object value) +103
ASP._Page_Views_Report_Index_cshtml.Execute() in c:\Program Files (x86)\Progress\Telerik Report Server\Telerik.ReportServer.Web\Views\Report\Index.cshtml:242
System.Web.WebPages.WebPageBase.ExecutePageHierarchy() +252
System.Web.Mvc.WebViewPage.ExecutePageHierarchy() +148
System.Web.WebPages.StartPage.ExecutePageHierarchy() +86
System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage) +107
System.Web.Mvc.ViewResultBase.ExecuteResult(ControllerContext context) +378
System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilterRecursive(IList`1 filters, Int32 filterIndex, ResultExecutingContext preContext, ControllerContext controllerContext, ActionResult actionResult) +91
System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilterRecursive(IList`1 filters, Int32 filterIndex, ResultExecutingContext preContext, ControllerContext controllerContext, ActionResult actionResult) +795
System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilterRecursive(IList`1 filters, Int32 filterIndex, ResultExecutingContext preContext, ControllerContext controllerContext, ActionResult actionResult) +795
System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilterRecursive(IList`1 filters, Int32 filterIndex, ResultExecutingContext preContext, ControllerContext controllerContext, ActionResult actionResult) +795
System.Web.Mvc.ControllerActionInvoker.InvokeActionResultWithFilters(ControllerContext controllerContext, IList`1 filters, ActionResult actionResult) +81
System.Web.Mvc.Async.<>c__DisplayClass3_1.<BeginInvokeAction>b__1(IAsyncResult asyncResult) +188
System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeAction(IAsyncResult asyncResult) +38
System.Web.Mvc.<>c.<BeginExecuteCore>b__152_1(IAsyncResult asyncResult, ExecuteCoreState innerState) +29
System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult) +73
System.Web.Mvc.Controller.EndExecuteCore(IAsyncResult asyncResult) +52
System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult) +39
System.Web.Mvc.Controller.EndExecute(IAsyncResult asyncResult) +38
System.Web.Mvc.<>c.<BeginProcessRequest>b__20_1(IAsyncResult asyncResult, ProcessRequestState innerState) +43
System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult) +73
System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult) +38
System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +646
System.Web.HttpApplication.ExecuteStepImpl(IExecutionStep step) +182
System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +134
I have converted the issue to a public bug report.
As a token of gratitude, I updated your Telerik points.
The problem doesn't occur when the Subject has valid content, so this would be the workaround.