When a user on a Apple Mac OSX client running Office for Mac 2011 clicks a previous version from the Version History of a document in SharePoint 2010 Document Library, their Office App will start but tell them "The address is not valid."  These are some tips to get around the issue.

Summary

SharePoint 2010 provides users with the ability to keep multiple versions of a single document within a Document Library.  This can be done either automatically for each save or via a Check-In/Check-Out method.  Microsoft Office for Mac 2011 allows users on an Apple computer running Mac OSX the ability to access these files directly and save them back to the server without the need for downloading/uploading the files.  This is in addition to the web based Office Web Apps that can view and edit the files as well.  However, the Office Web Apps cannot view the previous versions and the Office for Mac clients are not supported for viewing previous versions all though there have been sporadic reports of them working.

When the user attempts to view the current version of the file, it will open just fine.  However, if they go to the files drop down menu from within the Document Library and choose "Version History", if they click on any date other than the most recent, the following will happen:

1. Their browser will confirm they want to Open the file
2. The relevant Office application will open
3. The Office application will prompt the user to authenticate (if appropriate)
4. The Office application will provide a simple progress bar multiple times stating its downloading (about 3 times)
5. The Office application will then pop-up the following error dialog box:
   The address is not valid.
6. The user can then click OK but the file is not available.

Workaround for Mac Users

The users running on a Mac OSX can therefore not see the previous version without reverting it back to that version or performing the following operations to download a copy of the previous version to their local system.

• Go to the Document Library containing the file for which you want to view the previous version
• Hover over the file to display the drop down box and choose "Version History" (alternatively you can do this from the Ribbon above as well)
• With the version history showing the file you'd like to see, hold down the <control> key and Click with the mouse to pull up the context menu (Right-Click will also work)
• Choose "Download Linked File As..."
• Pick where to save the file and name it, then click "Save"
• Open the file from the local file system
  • NOTE:  Do not make changes to this version unless you want to wipe out all changes done in versions after it.
  • Best practice is to identify the pieces you want back, and open the current version from the SharePoint site, making changes there
• Remove the file you download from your local computer when you are done by dragging it to the trash can to conserve space and minimize confusion

References

• Open Office document previous version on Mac - Discussion board where this issue was discussed.
• Office for Mac 2011 and SharePoint integration features - Point of reference that Office for Mac 2011 is not included with a feature to "Track document versions from within Office documents."