Invalid character error from ScriptResource.axd

Solution:

Step 1: Turn off ScriptCombining on the ToolkitScriptManager

<ajaxToolKit:ToolkitScriptManager CombineScripts="false"  id="tkScriptManager" runat="server"></ajaxToolKit:ToolkitScriptManager>

Step 2: Turn off script compression

<system.web.extensions>
<scripting>
<scriptResourceHandler enableCompression="false" enableCaching="true"/>
</scripting>
</system.web.extensions>