2SXC Could not load file or assembly System.Web.Helpers

Trying to add I got an error.

Message:Could not load file or assembly 'System.Web.Helpers, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)

StackTrace:

at Connect.Dnn.Koi.DnnSkinFile.AutoDetect() at Connect.Koi.Context.HttpContextState.TryToDetectTheCssFramework() at Connect.Koi.Context.HttpContextState.get_CssFramework() at Connect.Koi.Context.ToolsForCurrentState.get_Css() at Connect.Koi.Koi.get_IsUnknown() at ASP._Page_Portals_31_2sxc_Content__Shared___Koi_Admin_Messages_cshtml.Execute() in c:\webapps\DNN7\Portals\31\2sxc\Content_Shared - Koi Admin Messages.cshtml:line 8 at System.Web.WebPages.WebPageBase.ExecutePageHierarchy() at System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage) at System.Web.WebPages.WebPageBase.<>c__DisplayClass7.b__6(TextWriter writer) at System.Web.WebPages.WebPageBase.Write(HelperResult result) at ASP._Page_Portals_31_2sxc_Content__Shared___Assets_cshtml.Execute() in c:\webapps\DNN7\Portals\31\2sxc\Content_Shared - Assets.cshtml:line 2 at System.Web.WebPages.WebPageBase.ExecutePageHierarchy() at System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage) at System.Web.WebPages.WebPageBase.<>c__DisplayClass7.b__6(TextWriter writer) at System.Web.WebPages.WebPageBase.Write(HelperResult result) at ASP._Page_Portals_31_2sxc_Content__Link___List_of_icon_links_cshtml.Execute() in c:\webapps\DNN7\Portals\31\2sxc\Content_Link - List of icon-links.cshtml:line 4 at System.Web.WebPages.WebPageBase.ExecutePageHierarchy() at System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage) at ToSic.Sxc.Engines.Razor.RazorEngine.Render(TextWriter writer) in C:\Projects\2sxc-dnn742\Website\DesktopModules\ToSIC_SexyContent\2Sexy Content Razor\Engines\Razor\RazorEngine.cs:line 75 at ToSic.Sxc.Engines.Razor.RazorEngine.RenderTemplate() in C:\Projects\2sxc-dnn742\Website\DesktopModules\ToSIC_SexyContent\2Sexy Content Razor\Engines\Razor\RazorEngine.cs:line 100 at ToSic.Sxc.Engines.EngineBase.Render() in C:\Projects\2sxc-dnn742\Website\DesktopModules\ToSIC_SexyContent\ToSic.Sxc\Engines\EngineBase.cs:line 106 at ToSic.SexyContent.CmsInstance.Render() in C:\Projects\2sxc-dnn742\Website\DesktopModules\ToSIC_SexyContent\ToSic.Sxc\SexyContent\SxcInstance_Render.cs:line 58

InnerMessage:

InnerStackTrace:

Source:Connect.Dnn.Koi

FileName:

FileLineNumber:0

FileColumnNumber:0

Method: