Website AJAX Errors

We rebooted our server, and all of sudden all of our sites started throwing this error. Looks like ScriptManager is not being recognized. I tried to roll back, reinstall change app pool but getting this error. E开发者_StackOverflow社区verywhere we are doing webservice calls, we are getting this error. Is there a quick fix to it? Here are the errors

Webpage error details

Message: 'Sys' is undefined


Sys.Application.initialize();
Sys.WebForms.PageRequestManager._initialize('ctl00$ScriptManager1', document.getElementById('aspnetForm'));
Sys.WebForms.PageRequestManager.getInstance()._updateControls([], [], [], 90);

Please help.

Can it be that the web.config somehow has been changed?

Can you verify that something like this exists in the web.config file?

<add verb="GET"
  path="ScriptResource.axd"
  type="Microsoft.Web.Handlers.ScriptResourceHandler"
  validate="false"/>

If not, this might result in the error you are getting..