Andrei Smolin

Outlook 2010 – 2016 doesn’t let you set WebViewUrl and WebViewOn

We’ve started a new line of blogs to inform Office [and Add-in Express] developers about [serious] problems [and solutions] related to Microsoft Office [and/or Add-in Express products] as early as possible.


This blog is about a recent change in Outlook 2010 – 2016: changing the WebViewUrl and WebViewOn properties of the Outlook.Folder (Outlook.MAPIFolder) object raises an exception. Outlook users who have a delayed access to Outlook updates may still be unaware of the issue.

To find out if your Outlook is affected by this issue, right-click an Outlook folder and pay attention to the Home tab: if the Home tab is missing, your Outlook is affected.

The folder Properties dialog. The Home tab is in place
The folder Properties dialog. The Home tab is missing

The only Add-in Express related aspect of this issue is: the WebViewPane region that Add-in Express provides to let you embed your forms into Outlook windows is affected; your form won’t be shown in that region if a corresponding Outlook update is installed.


Microsoft introduced this change to deal with a security issue.


Microsoft describes the issue and provides possible workarounds on this page. Note that it describes two issues; you may need to solve both of them.

A registry change to let your code change the WebViewUrl and WebViewOn properties

Extra info

The registry key to be changed depends on the Outlook version used. You need to specify the EnableRoamingFolderHomepages registry value in the following registry keys for the following Outlook versions:

Outlook 2016 Computer\HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\Security
Outlook 2013 Computer\HKEY_CURRENT_USER\Software\Microsoft\Office\15.0\Outlook\Security
Outlook 2010 Computer\HKEY_CURRENT_USER\Software\Microsoft\Office\14.0\Outlook\Security

In addition to the above said, that page describes a registry change that you need to do to let the WebViewUrl and WebViewOn properties work on a non-default Outlook message store.


20-Dec-2017. We’ve created a sample project that emulates the WebViewPane layout by turning off the Reading Pane and using the FolderView layout in an Add-in Express based add-in. The project is in C#; let me know if you need a VB.NET one. The project is here, the FolderView layout is briefly described here.


  • Andrew A says:

    Hi – Has anyone had any feedback from Office 2010 users that adding in the registry key fix doesn’t re-enable the Home Page tab? It seems to work for almost all cases but there are a couple of instances where adding the key seems to have no effect.

    Anyone else had this reported?

  • Andrei Smolin (Add-in Express Team) says:

    Hello Andrew,

    The article mentioned in the Workaround section ( contains solutions for *two* issues preventing a folder home page from showing up: 1) the above-described issue, 2) a much older issue that prevented showing Folder Home pages on a non-default message store (say, on a PST added to your Exchange profile). There’s a registry fix for the second issue as well; see that page.

  • elena says:

    I’m not able to find EnableRoamingFolderHomepages in registry


    any idea?

    thank you.

  • Andrei Smolin (Add-in Express Team) says:

    Hello Elena,

    You need to create EnableRoamingFolderHomepages. By default, it does not exist there.

  • Elena Aralla says:

    Thank you, Andrei.

    problem solved :)

    Now, I’ve some problems debugging your VebViewEmulate Add-in on Outlook 2010

    the problem is that add-in is successfully registered, but it’s listed in “Not-Active” Add-on on OutLook 2010

    no adxregistrator.log found, and no log on adxloader.log

    Same problem with my Add-in…

    I’ve installed the last version of add-in express (8.7.4430); i’m using Visual Studio 2010, on Windows XP professional, version 2002, SP3.

    This PC is installed on a virtual machine (VMWare)

    any suggestions are welcome.

    Thank you.

  • Andrei Smolin (Add-in Express Team) says:

    Ah, there’s a bug that prevents loading an add-in on Windows XP. Please install 8.6. As to the log files, version 8.7 (and subsequent versions) moves their default location to %temp%\{add-in project name}.

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