Here's what I had to do when I got the message on my Android device (Nexus 6). 1. Using an Android file manager app, I renamed the folder in a custom location that I was trying to sync to something else. e.g., "reddit_sync" to "reddit_syncx" 2. I made a new folder with the name of the original in the same location. e.g., "reddit_sync" 3. Then I proceeded to connect the folders again. I used the QR code from my desktop BitTorrent Sync application. Since they are both empty at this juncture, it should connect successfully. 4. Then move (or copy if you're paranoid) the files back from the folder you renamed in step 1 into the connected new one. Voila. Things should start syncing.