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 here.

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.

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