Need help to solve error "Error loading RadChart image"

[Karthik]

Hi Team,

We have updated .net framework 2.0 to 4.6 and  telerik version from 2010.2.826.20 to 2015.3.1111.45.

When the property UseSession is set to false 
We are getting an error as "Error loading RadChart image. You may also wish to check the ASP.NET Trace for further details. Display stack trace?". But I have found images are created in our TempImagesFolder(Cache). We never got this error in old version of telerik 2010.2.826.20. 
We are looking for best solution to fix this error with RadChart. As per the suggestion to replace RadChart with RadHtmlChart in Telerik sites that we found.  But in our case we are using RadChart in many parts of our application which not so easy to replace with RadHtmlChart. Please respond ASAP.

My chart image URL using browser's inspect element:http://localhost/xxx/ChartImage.axd?UseSession=false&ImageName=QbDPL66p6bEOlWq11Jibbiw64o%2btmhgdzHCOXHygpp8J9SSzUoHkZQzy0JrAcin0n5iitJHqTmroD5MwMSR20g%3d%3d&imageFormat=Png 


Below are the additional details. 

IIS 7.5
.Net 4.6

Code from ASPX Page
<telerik:RadChart ID="rchFMA" runat="server" Width="315px" DefaultType="Pie" Height="200px" AutoLayout="true" AutoTextWrap="true" Skin="WebBlue" TempImagesFolder="/Cache/" UseSession="false" IntelligentLabelsEnabled="true"> 
<Series> 
</Series> 
</telerik:RadChart> 

 
Code from webconfig
<system.web>
    <httpHandlers>     
      <add path="ChartImage.axd" type="Telerik.Web.UI.ChartHttpHandler" verb="*" validate="false"/>
    </httpHandlers>
</system.web>
<system.webServer>    
    <handlers>
      <add name="ChartImage_axd" path="ChartImage.axd" type="Telerik.Web.UI.ChartHttpHandler" verb="*" preCondition="integratedMode"/>
    </handlers>
 </system.webServer>

[Danail Vasilev]

Hello Karthik,

Currently I can only provide a link to a forum thread that treats a similar issue - http://www.telerik.com/forums/error-loading-radchart-image-6a4ac2cb656b

Please note that RadChart has already been obsoleted and we do not provide support for it anymore. Therefore we strongly suggest to upgrade to the newer RadHtmlChart. You can find details regarding upgrading in this section - http://docs.telerik.com/devtools/aspnet-ajax/controls/htmlchart/changes-and-backwards-compatibility/migrating-from-radchart-to-radhtmlchart/migrate-functionalities---features-and-series-types-parity

The RadHtmlChart controls also has a new modern look and feel, it provides many series and features and also the mentioned error is not reproducible there.

Regards,
Danail Vasilev
Telerik

[Karthik]

Thanks for the reply.

As we are using webfarms, So we set UseSession=false and TempImagesFolder=XXXXX. Images are created in TempImagesFolder, but they are not loading.
If we use UseSession=true then sessionid might get lost in the webfarm, So can you please provide a solution for UseSession=false until we migrate to RadHTMLChart. As we used RadChart many of the pages, So it might take atleast 3months to migrate to RadHTMLchart.

[Danail Vasilev]

Hello Karthik,

You can try also the following troubleshooting steps:
     - See how to integrate Telerik UI controls in a webfarm scenario in this blog post - http://www.telerik.com/blogs/integrate-radcontrols-for-asp.net-ajax-in-a-webfarm-or-webgarden
    - Use a sticky session to ensure the client request is handled by the same machine or configure a shared session with SQL server or session state server. See this forum for details - http://www.telerik.com/forums/chartimage-in-webfarm
    - Make a further investigation regarding the session sharing between webfarms on the Internet - https://www.google.bg/search?q=share+session+between+webfarm&gws_rd=cr&ei=BuuxVuDJIoezsQGH7JfoAw

Regards,
Danail Vasilev
Telerik