DNN 5 load error (NullReferenceException) under IE11

Question

I've been asked to troubleshot legacy website created using DNN5.0

Problem exists only when IE11 is used. In previous versions everything is ok, as well as when using other browsers (Chrome, Firefox).

I've managed to discover that this is caused by user agent sent from IE to a server. When it's set to default IE11 value (User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; Trident/7.0; rv:11.0) like Gecko DNN generates error, when I change it using developer tools to IE10 one (User-Agent: Mozilla/5.0 (compatible; MSIE 10.0; Windows NT 6.2; Trident/6.0)) website loads without any problem. Adding website to compatibility view list also helps - it's changing user agent too: User-Agent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.1; WOW64; Trident/7.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; Media Center PC 6.0; .NET4.0C; .NET4.0E; InfoPath.3).

Is it possible to change DNN behaviour when it service requests with default IE11 user-agent header to a IE10 user-agent behaviour? I haven't googled anything interesting.

Error details:

InnerException: Object reference not set to an instance of an object.

Method: DotNetNuke.UI.WebControls.MenuNodeWriter.Render

StackTrace:

Message: DotNetNuke.Services.Exceptions.PageLoadException: Object reference not set to an instance of an object. ---> System.NullReferenceException: Object reference not set to an instance of an object. at DotNetNuke.UI.WebControls.MenuNodeWriter.Render(HtmlTextWriter writer) at DotNetNuke.UI.WebControls.MenuNodeWriter.RenderNode(HtmlTextWriter writer, MenuNode Node) at DotNetNuke.UI.WebControls.MenuNode.Render(HtmlTextWriter writer) at DotNetNuke.UI.WebControls.DNNMenuWriter.RenderChildren(HtmlTextWriter writer) at DotNetNuke.UI.WebControls.DNNMenuWriter.RenderContents(HtmlTextWriter writer) at System.Web.UI.WebControls.WebControl.Render(HtmlTextWriter writer) at System.Web.UI.Control.RenderControlInternal(HtmlTextWriter writer, ControlAdapter adapter) at System.Web.UI.Control.RenderControl(HtmlTextWriter writer, ControlAdapter adapter) at System.Web.UI.Control.RenderControl(HtmlTextWriter writer) at DotNetNuke.UI.WebControls.DNNMenuWriter.RenderMenu(HtmlTextWriter writer, DNNMenu Menu) at DotNetNuke.UI.WebControls.DNNMenu.Render(HtmlTextWriter writer) at System.Web.UI.Control.RenderControlInternal(HtmlTextWriter writer, ControlAdapter adapter) at System.Web.UI.Control.RenderControl(HtmlTextWriter writer, ControlAdapter adapter) at System.Web.UI.Control.RenderControl(HtmlTextWriter writer) at System.Web.UI.Control.RenderChildrenInternal(HtmlTextWriter writer, ICollection children) at System.Web.UI.Control.RenderChildren(HtmlTextWriter writer) at System.Web.UI.Control.Render(HtmlTextWriter writer) at System.Web.UI.Control.RenderControlInternal(HtmlTextWriter writer, ControlAdapter adapter) at System.Web.UI.Control.RenderControl(HtmlTextWriter writer, ControlAdapter adapter) at System.Web.UI.Control.RenderControl(HtmlTextWriter writer) at ASP.portals__default_skins_minimalextropy_index_ascx._Render_control1(HtmlTextWriter __w, Control parameterContainer) at System.Web.UI.Control.RenderChildrenInternal(HtmlTextWriter writer, ICollection children) at System.Web.UI.Control.RenderChildren(HtmlTextWriter writer) at System.Web.UI.Control.Render(HtmlTextWriter writer) at System.Web.UI.Control.RenderControlInternal(HtmlTextWriter writer, ControlAdapter adapter) at System.Web.UI.Control.RenderControl(HtmlTextWriter writer, ControlAdapter adapter) at System.Web.UI.Control.RenderControl(HtmlTextWriter writer) at System.Web.UI.Control.RenderChildrenInternal(HtmlTextWriter writer, ICollection children) at System.Web.UI.Control.RenderChildren(HtmlTextWriter writer) at System.Web.UI.Control.Render(HtmlTextWriter writer) at System.Web.UI.Control.RenderControlInternal(HtmlTextWriter writer, ControlAdapter adapter) at System.Web.UI.Control.RenderControl(HtmlTextWriter writer, ControlAdapter adapter) at System.Web.UI.Control.RenderControl(HtmlTextWriter writer) at System.Web.UI.Control.RenderChildrenInternal(HtmlTextWriter writer, ICollection children) at System.Web.UI.Control.RenderChildren(HtmlTextWriter writer) at System.Web.UI.HtmlControls.HtmlForm.RenderChildren(HtmlTextWriter writer) at System.Web.UI.HtmlControls.HtmlContainerControl.Render(HtmlTextWriter writer) at System.Web.UI.HtmlControls.HtmlForm.Render(HtmlTextWriter output) at System.Web.UI.Control.RenderControlInternal(HtmlTextWriter writer, ControlAdapter adapter) at System.Web.UI.Control.RenderControl(HtmlTextWriter writer, ControlAdapter adapter) at System.Web.UI.HtmlControls.HtmlForm.RenderControl(HtmlTextWriter writer) at System.Web.UI.Control.RenderChildrenInternal(HtmlTextWriter writer, ICollection children) at System.Web.UI.Control.RenderChildren(HtmlTextWriter writer) at System.Web.UI.HtmlControls.HtmlContainerControl.Render(HtmlTextWriter writer) at System.Web.UI.Control.RenderControlInternal(HtmlTextWriter writer, ControlAdapter adapter) at System.Web.UI.Control.RenderControl(HtmlTextWriter writer, ControlAdapter adapter) at System.Web.UI.Control.RenderControl(HtmlTextWriter writer) at ASP.default_aspx._Render_control1(HtmlTextWriter __w, Control parameterContainer) at System.Web.UI.Control.RenderChildrenInternal(HtmlTextWriter writer, ICollection children) at System.Web.UI.Control.RenderChildren(HtmlTextWriter writer) at System.Web.UI.Page.Render(HtmlTextWriter writer) at DotNetNuke.Framework.PageBase.Render(HtmlTextWriter writer) at System.Web.UI.Control.RenderControlInternal(HtmlTextWriter writer, ControlAdapter adapter) at System.Web.UI.Control.RenderControl(HtmlTextWriter writer, ControlAdapter adapter) at System.Web.UI.Control.RenderControl(HtmlTextWriter writer) at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) --- End of inner exception stack trace ---

Answer 1

I had the same problem, and you are correct in your identification of the user agent string.

Add a browserCaps section to your web.config to patch around it. I used the following:

  <system.web>
    <browserCaps>
      <!-- IE 11 Patch //-->
      <case match="Trident\/7.0; rv:(?'version'(?'major'\d+)(\.(?'minor'\d+)?)(?'letters'\w*))(?'extra'[^)]*)">
        browser=IE
        layoutEngine=Trident
        layoutEngineVersion=0${layoutVersion}
        frames=true
        tables=true
        cookies=true
        javascript=true
        javaapplets=true
        ecmascriptversion=1.5
        w3cdomversion=1.0
        css1=true
        css2=true
        xml=true
        tagwriter=System.Web.UI.HtmlTextWriter
        screenBitDepth=8
        isColor=true
        extra=${extra}
        letters=${letters}
        <case match="rv:(?'version'(?'major'\d+)(?'minor'\.\d+)(?'letters'\w*))">
          version=${version}
          majorversion=0${major}
          minorversion=0${minor}
          type=IE${major}
        </case>
      </case>
    </browserCaps>

Answer 2

Could be this: http://www.hanselman.com/blog/IE10AndIE11AndWindows81AndDoPostBack.aspx

I would suggest following the document upgrade path in DNN and upgrade to a more recent version and see if your problem goes away.

http://www.dnnsoftware.com/wiki/page/suggested_upgrade_path

Obviously back everything up and do this in a development / staging environment not live.