I am facing the  issue (Multiple references of version of  telerik DLL) while upgrading the DNN version from 04.09.00 to 05.06.00.
Actual error is: Project currently contains the reference to more then one version of Telerik.Web.UI, a direct reference to version 2008.3.1125.35 and an indirect reference (through dotNetNuke.Web.UI.WebControls.DNNWindowManager) to version 2010.2.925.35. Change the direct reference to use version 2010.2.925.35 (or higher) of telerik.Web.UI

Same Problem has already been mentioned in the below thread: (Referred)http://www.dotnetnuke.com/Resources/Forums/tabid/795/forumid/107/postid/401725/scope/posts/Default.aspx#401725

I have gone though all the replies of that post, but still facing issue.

Before update, I am using telerik version 2008.3.1125.35 (I have the developer licence of  this version individually). After updation, it automatically updated to version 2010.2.929.35(This is the default version of telrik DLL provided in the DNN version 5.6).

I have checked in web.config file, as you mentioned in above reply:

1. (Before updates, these lines are not available in the web.config, below lines has been added after updation)
<assemblyIdentity name="Telerik.Web.UI" publicKeyToken="121fae78165ba3d4" />
 <bindingRedirect oldVersion="2008.0.0.0-2020.0.0.0" newVersion="2010.02.0929.35" />                  </dependentAssembly>

2. Check the version of telerik DLL in the bin directory, found that it has also been updated from

2008.3.1125.35 to 2010.2.929.35.

Run the application with the above settings (Web portal has been run successfully, but this time it is using telerik version 2010.02.0929.353 and we are facing lot of designing issues with the new version of telerik DLL)

Our basic requirement is to upgrade only the DNN version but not Telerik DLL version.

3. Removed the reference of telerik DLL 2010 verion and again added reference of old 2008  telerik DLL version.

4. Changed the settings in web.config file.(Chnaged the newVersion attribute value to the 2008.3.1125.35 )

<assemblyIdentity name="Telerik.Web.UI" publicKeyToken="121fae78165ba3d4" />

                <bindingRedirect oldVersion="2008.0.0.0-2020.0.0.0" newVersion=" 2008.3.1125.35" />    </dependentAssembly>

5. Also checked in GAC, No telerik DLL is available/ installed in GAC.

6. Run the application . with the new  settings.

Again found the same error (Multipe reference for telerik DLL )

  Error:************************************************************************************************

Compiler Error Message: BC32206: The project currently contains references to more than one version of Telerik.Web.UI, a direct reference to version 2008.3.1125.35 and an indirect reference (through 'DotNetNuke.Web.UI.WebControls.DnnWindowManager') to version 2010.2.929.35. Change the direct reference to use version 2010.2.929.35 (or higher) of Telerik.Web.UI.

Source Error:

Line 30:         <input id="ScrollTop" runat="server" name="ScrollTop" type="hidden" />

Line 31:         <input id="__dnnVariable" runat="server" name="__dnnVariable" type="hidden" />

Line 32:         <dnnui:DnnWindowManager ID="DnnWindowManager" runat="server" Visible="False">

Line 33:         </dnnui:DnnWindowManager>

Line 34:     </dnn:Form>

Source File: C:\centrum\CentumOnline\Default.aspx    Line: 32

******************************************************************************************************

Please suggest .