I have recently updated a DNN 7 site to DNN9.1.1. The site includes a couple of modules that were originally developed for DNN6 using web forms and Telerik Web Controls for DNN. As required for DNN9, I have recompiled these modules against DNN8 Core and the sunset version of the Telerik controls (2013.2.717.40). 

The site works correctly in a default IIS website configuration in my local development environment, but when I deploy it to my hosting provider's server, whenever I click on a button (eg paging, sorting etc) in the Telerik grid, an exception is thrown (see below).

Can anyone suggest what may be causing this please?

[NotSupportedException: Collection is read-only.]
   System.Collections.Specialized.NameObjectCollectionBase.BaseSet(String name, Object value) +6664741
   System.Web.HttpServerVarsCollection.SetServerVariableManagedOnly(String name, String value) +117
   System.Web.HttpServerVarsCollection.SynchronizeServerVariable(String name, String value, Boolean ensurePopulated) +51
   System.Web.HttpRequest.SynchronizeServerVariable(String name, String value) +114
   System.Web.Hosting.IIS7WorkerRequest.GetServerVarChanges(HttpContext ctx) +314
   System.Web.Hosting.IIS7WorkerRequest.SynchronizeVariables(HttpContext context) +9944570
   System.Web.HttpRuntime.ProcessRequestNotificationPrivate(IIS7WorkerRequest wr, HttpContext context) +151