We get the above error when upgrading to 0.8.1.

The script manager control IS on the page that throws the error.

<body>
    <form id="formPopAssetDetail" runat="server" class="DolPopupScreen" enableviewstate="false">
    
     <ext:ScriptManager ID="extScriptManager" runat="server" CleanResourceUrl="true" EnableViewState="false" />