MSCharts “No http handler was found for request type ‘GET'” error

This is what you need for ASP.NET 4.0 / IIS 7.5 on Windows 7:

Your web.config must contain the following:

<appSettings>
  <add key="ChartImageHandler" value="storage=file;timeout=20;" />
</appSettings>


<compilation targetFramework="4.0">
 <assemblies>
  <add assembly="System.Web.DataVisualization, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
 </assemblies>
</compilation>

<system.webServer>

<handlers>
      <add name="ChartImg" verb="*" path="ChartImg.axd"  type="System.Web.UI.DataVisualization.Charting.ChartHttpHandler, System.Web.DataVisualization, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"  />
    </handlers>
</system.webServer>

You also need this at the top of your aspx page:

<%@ Register Assembly="System.Web.DataVisualization, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"
    Namespace="System.Web.UI.DataVisualization.Charting" TagPrefix="asp" %>

Hope this helps