The WebDAV Launcher Office Connector is not signed correctly and so does not install or run in Firefox 43.0 or greater. This is a recent change in Mozilla policy for extension signing.
- Firefox 43.0 or higher
- WebDAV Launcher 126.96.36.199-signed
- Windows, Linux or Mac
- Go to Help > About Firefox
- Make sure Firefox is version 43.0 or higher
- Uninstall the WebDav Launcher
- Go to a page with a Word document as an attachment
- Click on the Word document
- Click ... > Edit in Office
- Click Ok for the Download box
- Click Allow
The document should load in Word
The Firefox add-on is not added. If it is already added, it will not work. The Add-on shows
The WebDAV launcher is disabled with the message
- Download the plugin directly from mozilla (using Chrome so it doesn't auto install) https://addons.mozilla.org/firefox/downloads/file/259818/webdav_launcher-1.0.8-fx.xpi
- Go to about:addons, then Cog Menu > Install Add-On from file and select the .xpi file
- Click Install on the pop-up box, then Restart
- Go the location bar and enter about:config
- Click I'll be careful, I promise!
- In the new Search field at the top enter xpinstall.signatures.required
- Double click the entry to make it false
You can also put this entry in user.js in the firefox profile directory
The plugin will now work.