I've been using BTSync for a while now and it's absolutely fantastic! I've just set it up to sync a load of my files between my computer, an external hard drive in my house connected to a Raspberry Pi, and a second Raspberry Pi and external hard drive in my parents house. This had been working very well but today I rebooted the Pi at my parents house and when it came on the GUI (ipAddress:8888/gui) prompted for an account to be created and then showed the no folders message. On the other syncing devices it shows it as offline. I copied the contents of the .sync folder somewhere else so I could preserve it. Looking inside I saw that there were files called history.dat.old, settings.dat.old and sync.dat.old along side the same files without the .old extension. history.dat.old and sync.dat.old contain different things to their "new" counterparts but settings.dat.old appears to be the same (although it is just one long line so I may well have missed something). I tried renaming the .dat.old files to be the .dat files and the .dat files to be the .dat.old files and then restarting again but basically the same happened again. I've got quite a number of large folders synced between the two so I'd really rather not have to redo all the syncing if I can possibly avoid it. More than that I'd like to know how it happened and how I can stop it from happening again. Any help would be greatly appreciated.