Get "Invalid URI: The URI scheme is not valid" Ope

I have a site that's been migrated from Sitefinity 3.7 to 4.2 (with SP1 applied). In the administrative interface, when I go Administration>Backend Pages, the  Sitefinity group page appears on the screen. When I click the arrow to expand the node an alert message appears: "Invalid URI: The URI scheme is not valid." When I dismiss the alert the Loading message and loader animation are sitting on the page and no child pages are appearing under the Sitefinity node. If I refresh the page I get the same invalid URl alert message on page load.

Looking at the net traffic In firebug (I'm using FF 7, but it also happens in Chrome 12 and IE9) the issue seems to be with this call:
localhost/.../.

The post data for this request is JSON with the value of ["f669d9a7-009d-4d83-ddaa-000000000004"], which is the id of the Sitefinity node. The response is just:"Detail":"Invalid URI: The URI scheme is not valid."

Hello Brandon ,

It looks like the system cannot render the tree containing the pages. Have you installed custom modules to your website recently or added other type of content?

Regards,
Victor Velev
the Telerik team

Yes, in fact we are trying to add a custom module which is essentially a rebuild of a rebuild of a module from the old site on 3.7.

I'm trying to run a trace, but when I add the <system.diagnostics> node to the web.config I get an exception:

Unable to load one or more of the requested types. Retrieve the LoaderExceptions property for more information.

I too am getting this message when I attempt to access the Backend pages. I just recently upgraded to build 1733. I don't go into the backend to often so I can't say for cetain when this started happening but I know it is within the past 2 weeks and that is when I upgraded from 1655 to 1733. I do have some custom modules. Is there a way to systematically troubleshoot this by removing custom modules from the backend without doing full restores to sql?

Can I follow this post to completely remove a single custom module (including the back-end related items that might be causing this issue)? http://www.sitefinity.com/devnet/forums/sitefinity-4-x/general-discussions/impossible-to-uninstall-module.aspx

Thanks.

Hello Jeff,

@Brandon: I have answered you in the support ticket.

@Jeff: You can follow the thread and remove the custom modules to see which one is actually giving you troubles. Do not forget to edit your SystemConfig as described and also perform the process on a backup copy of your website.

Best wishes,
Victor Velev
the Telerik team