Office XP running on Windows 7 fails to open Excel and Powerpoint documents on Webdav share : URLREWRITE to the rescue!

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I've recently worked on a problem dealing with Office XP failing to open Excel and Powerpoint document under the following client/server configuration:

Client

  • OS = Windows 7
  • Office XP
  • WEBDAV redirector used to map a network drive (net use z: https://server/share)

Server

  • OS = Windows 2008 R2
  • IIS 7.5 with Webdav module

Whenever a client was trying to open a XLS or PPT file, an error was occurring:

 

As you can see, the document path is prefixed by "DavWWWRoot". This is causing WEBDAV requests to be issued on a non-existing path. I'm not going to provide details on this but I'm suspecting this is due to the way WEBDAV shares are mounted on Windows 7. Typically, the Windows 7 Explorer is showing WEBDAV drives like this :

Hopefully, IIS provides a URL rewrite module which can be used to workaround the issue using a simple rewriting rule suppressing /DavWWWRoot from the URL requested:

Alternatively, you can define the above rule in your web.config :

  <rewrite>
            <rules>
                <rule name="TEST" stopProcessing="true">
                    <match url="^DAVWWWRoot/(.*)" />
                    <action type="Rewrite" url="{R:1}" logRewrittenUrl="true" />
                </rule>
            </rules>
        </rewrite>

With this rule in place, you should have no more issue to open XLS and PPT files on the WEBDAV mapped drive.

Notes:

  • the above workaround only works if the WEBDAV redirector is used to mount a share on port 80 (Office XP uses a different code path (MSAIPP) when port other than 80 is used)
  • the issue could likely be resolved by a code change in Office XP. However, this version of Office is no more supported
  • Latest Office version has no problem to open documents on WEBDAV shares

I hope this "trick" will be helpful to people who are still using Office XP.

Emmanuel Boersma