If I upgraded from DNN version 4.4 to version 4.9.5 and then to version 6.1.2 then it gives me the error
Error: Buying is currently unavailable. DotNetNuke.Services.Exceptions.ModuleLoadException: The type initializer for 'DotNetNuke.Modules.Html.DataProvider' threw an exception. ---> System.TypeInitializationException: The type initializer for 'DotNetNuke.Modules.Html.DataProvider' threw an exception. ---> System.InvalidCastException: Unable to cast object of type 'DotNetNuke.Modules.HTML.SqlDataProvider' to type 'DotNetNuke.Modules.Html.DataProvider'. at DotNetNuke.Modules.Html.DataProvider.CreateProvider() at DotNetNuke.Modules.Html.DataProvider..cctor() --- End of inner exception stack trace --- at DotNetNuke.Modules.Html.DataProvider.Instance() at DotNetNuke.Modules.Html.WorkflowStateController.GetWorkflows(Int32 PortalID) at DotNetNuke.Modules.Html.HtmlTextController.GetWorkflow(Int32 ModuleId, Int32 TabId, Int32 PortalId) at DotNetNuke.Modules.Html.HtmlModule.OnInit(EventArgs e) --- End of inner exception stack trace ---
For HTML module only
Like Devjosh said, it appears your HTML module was incorrectly installed. You will need to replace the DotNetNuke.Modules.Html.dll file in your DotNetNuke installation's "bin" folder. If you can login to the site, you can also try re-installing the module by going to the Host > Extensions page, clicking the "Available Extensions" tab, expanding the "Modules" section, then clicking the "Install" button next to the HTML module.