Commented Issue: EnableCDN does not work on ToolkitScriptManager on .NET 4.5 [27353]

Created ASP.NET page using .NET 4.5. Added a updatepanel with a timer in it and using ToolkitScriptManager. If you set EnableCDN then the timer ajax postbacks fail.
This fails on all versions of AjaxControlToolkit.

Only way to fix this is to set EnableCdnFallback="False"

Here's the controls on the page.

<ajaxToolkit:ToolkitScriptManager runat="server" EnableCdn="True" EnableCdnFallback="True"/>
<asp:UpdatePanel runat="server">
<ContentTemplate>
<asp:Timer runat="server" ID="tm" Interval="1000" OnTick="tm_Tick"></asp:Timer>
</ContentTemplate>
</asp:UpdatePanel>


The error:

Uncaught Sys.WebForms.PageRequestManagerParserErrorException: Sys.WebForms.PageRequestManagerParserErrorException: The message received from the server could not be parsed. Common causes for this error are when the response is modified by calls to Response.Write(), response filters, HttpModules, or server trace is enabled.
Details: Unknown token: 'fallbackScript'.

Thanks
James
Comments: I'm seeing the same issue since upgrading a site to .NET 4.5. A similar site with an exact copy of a particular page but running under .NET 4.0 doesn't display this error when using the CDN to serve scripts.