I am using DNN 5.1.

Yesterday I installed a trial version of Cute Editor and after that I noticed that the titles in the MLHTML modules were not showing. Then late last night, I got the following error messages:

An error has occurred. 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() --- End of inner exception stack trace --- at DotNetNuke.Modules.Html.HtmlTextController.GetTopHtmlText(Int32 ModuleID, Boolean IsPublished, Int32 WorkflowID) at DotNetNuke.Modules.Html.HtmlModule.get_ModuleActions() at DotNetNuke.UI.Modules.ModuleInstanceContext.LoadActions(HttpRequest Request) at DotNetNuke.UI.Modules.ModuleInstanceContext.get_Actions() at DotNetNuke.UI.Containers.ActionBase.Page_Load(Object sender, EventArgs e) --- End of inner exception stack trace ---

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Error: Enter Title 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() --- End of inner exception stack trace --- at DotNetNuke.Modules.Html.HtmlTextController.GetTopHtmlText(Int32 ModuleID, Boolean IsPublished, Int32 WorkflowID) at DotNetNuke.Modules.Html.HtmlModule.Page_Load(Object sender, EventArgs e) --- End of inner exception stack trace ---

and also this one:

An error has occurred. 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() --- End of inner exception stack trace --- at DotNetNuke.Modules.Html.HtmlTextController.GetTopHtmlText(Int32 ModuleID, Boolean IsPublished, Int32 WorkflowID) at DotNetNuke.Modules.Html.HtmlModule.get_ModuleActions() at DotNetNuke.UI.Modules.ModuleInstanceContext.LoadActions(HttpRequest Request) at DotNetNuke.UI.Modules.ModuleInstanceContext.get_Actions() at DotNetNuke.UI.Containers.ActionBase.Page_Load(Object sender, EventArgs e) --- End of inner exception stack trace ---

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Error: Text/HTML 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() --- End of inner exception stack trace --- at DotNetNuke.Modules.Html.HtmlTextController.GetTopHtmlText(Int32 ModuleID, Boolean IsPublished, Int32 WorkflowID) at DotNetNuke.Modules.Html.HtmlModule.Page_Load(Object sender, EventArgs e) --- End of inner exception stack trace ---

The google search returned references to the same problem but not real fix to it. There is a possible solution regarding quotation marks in the controls/texteditor.ascx. I tried it and the result is the same.

Can anyone provide guidance?

Did you try to restart the application?

Found it! When I restored the site locally I did it on a folder where a previous version of the website existed. That previous version had a previous version of the html module and on the latest version that module has moved from having the code on \app_code\html folder to being a compiled module. So the solution was to just remove the folder \App_Code\Html since it's no longer needed.

Hope this helps.