Error: does not contain a script with hash code "3cf12cf1'".

We are seeing quite a few of these errors on our site.

AjaxControlToolkit

Assembly "AjaxControlToolkit, Version=4.1.7.123, Culture=neutral, PublicKeyToken=28f01b0e84b6d53e" does not contain a script with hash code "3cf12cf1'".

DeserializeScriptEntries

   at AjaxControlToolkit.ToolkitScriptManager.DeserializeScriptEntries(String serializedScriptEntries, Boolean loaded)
   at AjaxControlToolkit.ToolkitScriptManager.OutputCombinedScriptFile(HttpContext context)
   at AjaxControlToolkit.ToolkitScriptManager.OnInit(EventArgs e)
   at System.Web.UI.Control.InitRecursive(Control namingContainer)
   at System.Web.UI.Control.InitRecursive(Control namingContainer)
   at System.Web.UI.Control.InitRecursive(Control namingContainer)
   at System.Web.UI.Control.InitRecursive(Control namingContainer)
   at System.Web.UI.Control.InitRecursive(Control namingContainer)
   at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)