SFB Client Error: You Don't Permissions Needed to Access File System

I recently had a user complain that they couldn't get their SFB client to sign-in...what's funny is we've been running SFB for over a year and they've never been able to use it.

When attempting to sign in, the following error is thrown:

Skype For Business can't sign in. You might not have the permissions needed for Skype For Business to access the Windows file system, or there might be a problem with your installation of Office.

The user can sign in on another machine, so it's definitely something wrong with this particular client and not their account.

The Problem:

After some digging, I checked the following path on the user's machine:

"%localappdata%/Microsoft/"

The "Office" folder didn't exist, which explains why there's a permission problem...can't have perms on a non-existent folder.

The Fix:

Completely close the SFB Client and Outlook

Copy the "%localappdata%/microsoft/office" folder from a working machine to the problem machine.

Start SFB and Outlook

Now the user should be able to sign-in!