RadChart has been replaced by RadHtmlChart, Telerik's client-side charting component. If you are considering RadChart for new development, examine the RadHtmlChart documentation and online demos first to see if it will fit your development needs. If you are already using RadChart in your projects, you can migrate to RadHtmlChart by following these articles: Migrating Series, Migrating Axes, Migrating Date Axes, Migrating Databinding, Features parity. Support for RadChart is discontinued as of Q3 2014, but the control will remain in the assembly so it can still be used. We encourage you to use RadHtmlChart for new development.
You may want to disable Session for a web application that contains a RadChart instance. The chart image is retrieved using Session so you are restricted from setting EnableSessionState false in your Page directive or web.config file.
To disable session state and still display the chart:
Set the RadChart UseSession property to False.
Create a temporary folder for the chart image.
Verify the web application has write permissions to the temporary folder.
Set the RadChart TempImagesFolder property to the path of the temporary folder.
The zoom and scroll features of RadChart require session state usage.