Improvvisamente e senza alcuna ragione, una mia applicazione su hostforlife.com ha smesso di funzionare correttamente.

La console degli errori di Firefox restituiva il seguente errore:

ASP.NET Ajax client-side framework failed to load
'Sys' is undefined.

esguendo pagine in cui era inserito <asp:ScriptManager ID=”ScriptManager1″ runat=”server” EnablePageMethods=”true”/>.

Ho risolto il problema aggiungendo nel web.config la seguente sezione:

<handlers> 
    <remove name="WebServiceHandlerFactory-Integrated"/> 
    <remove name="ScriptHandlerFactory"/> 
    <remove name="ScriptHandlerFactoryAppServices"/> 
    <remove name="ScriptResource"/> 
    <add name="ScriptHandlerFactory" verb="*" path="*.asmx" preCondition="integratedMode" type="System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/> 
    <add name="ScriptHandlerFactoryAppServices" verb="*" path="*_AppService.axd" preCondition="integratedMode" type="System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/> 
    <add name="ScriptResource" preCondition="integratedMode" verb="GET,HEAD" path="ScriptResource.axd" type="System.Web.Handlers.ScriptResourceHandler, System.Web.Extensions, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/> 
</handlers>