I have just completed an update from 5.05 to 6.1.1 and I am receiving an error when restarting the site. Is this just a permission issue if so what do I do to properly set the properties for this directory? This is the error description: Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.UnauthorizedAccessException:The stack trace:[UnauthorizedAccessException: Access to the path 'D:\Hosting\5192036\html\App_Data\ClientDependency' is denied.] System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath) +7716623 System.IO.Directory.InternalCreateDirectory(String fullPath, String path, DirectorySecurity dirSecurity) +7569401 System.IO.DirectoryInfo.Create() +15 ClientDependency.Core.CompositeFiles.Providers.XmlFileMapper.EnsureXmlFile() +106 ClientDependency.Core.CompositeFiles.Providers.XmlFileMapper.Initialize(HttpContextBase http) +139 ClientDependency.Core.Config.ClientDependencySettings.LoadDefaultFileMapConfig(ClientDependencySection section, HttpContextBase http) +124 ClientDependency.Core.Config.ClientDependencySettings.LoadProviders(ClientDependencySection section, HttpContextBase http) +415 ClientDependency.Core.Config.ClientDependencySettings..ctor() +94 ClientDependency.Core.Config.ClientDependencySettings.get_Instance() +78 ClientDependency.Core.Controls.ClientDependencyLoader..ctor() +97 DotNetNuke.Web.Client.ClientResourceManagement.ClientResourceLoader..ctor() +5 ASP.default_aspx.__BuildControlClientResourceLoader() +26 ASP.default_aspx.__BuildControlBody() +205 ASP.default_aspx.__BuildControlTree(default_aspx __ctrl) +75 ASP.default_aspx.FrameworkInitialize() +37 System.Web.UI.Page.ProcessRequest(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +56 System.Web.UI.Page.ProcessRequest() +80 System.Web.UI.Page.ProcessRequestWithNoAssert(HttpContext context) +21 System.Web.UI.Page.ProcessRequest(HttpContext context) +49 ASP.default_aspx.ProcessRequest(HttpContext context) +4 System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +181 System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +75

In case more people have this, I had the same problem.
It turns out that the \ClientDependency was a non existing folder so I solved it by simply adding the folder under app_data.

Hans-Ove