or
We are using windows8 r2 , IIS7.5 and web site is configured to use classic mode instead of Integrated mode. We have issues with Page methods failing when we use RadCompression in HttpModules. But the same setup works fine with integrated mode.
Here is the error message:
<httpModules>
<add name="RadCompression" type="Telerik.Web.UI.RadCompression"/>
</httpModules>
<system.webServer>
<validation validateIntegratedModeConfiguration="false"/>
<modules>
<add name="RadCompression" type="Telerik.Web.UI.RadCompression"/>
</modules>

<telerik:RadGrid ID="RadGrid1" runat="server" AllowSorting="true" ShowGroupPanel="true" GridLines="Both" ItemStyle-CssClass="RowStyle" AlternatingItemStyle-CssClass="AlternatingRowStyle" HeaderStyle-CssClass="HeaderStyle" SelectedItemStyle-CssClass="SelectedRowStyle" ClientSettings-Selecting-AllowRowSelect="true" ClientSettings-Resizing-AllowColumnResize="true" ClientSettings-Resizing-AllowRowResize="true" ClientSettings-Scrolling-AllowScroll="true" ClientSettings-Scrolling-UseStaticHeaders="true" ClientSettings-Scrolling-FrozenColumnsCount="1" ClientSettings-Scrolling-SaveScrollPosition="true" ClientSettings-AllowColumnsReorder="true" MasterTableView-AllowMultiColumnSorting="true" ClientSettings-ClientEvents-OnGridCreated="GridCreated" SortingSettings-SortedBackColor="Beige" SortingSettings-EnableSkinSortStyles="false" SortingSettings-SortToolTip="tri"> <ClientSettings AllowDragToGroup="true" /> <GroupingSettings ShowUnGroupButton="true" /> <ExportSettings IgnorePaging="true" > <Csv ColumnDelimiter="Semicolon" EncloseDataWithQuotes="true" /> </ExportSettings> </telerik:RadGrid> <asp:Button ID="btnExportCVS" runat="server" Text="Export" CssClass="CTAButton" Enabled="true" OnClick="btnExportCVS_OnClick"></asp:Button>protected void btnExportCVS_OnClick(object sender, EventArgs e){ this.RadGrid1.MasterTableView.ExportToCSV();}<telerik:RadEditor Skin="Default" ID="RadEditor1" EditModes="Preview" OnClientModeChange="OnClientModeChange" Enabled="true" runat="server" Width="100%" Height="150px" ToolsFile="~/includes/NoTools.xml"></telerik:RadEditor>function OnClientModeChange(editor, args) { var mode = editor.get_mode(); switch (mode) { case 1: //alert( "We are in Design mode"); //do something break; case 2: //alert("We are in HTML mode"); break; case 4: setTimeout(function () { var tool = editor.getToolByName("ToggleScreenMode"); tool.setState(0); }, 0); //alert( "We are in Preview mode"); //do something break; } }