I just performed a sync using BitTorrent Sync v1.4.110. I am 100% certain BitTorrent Sync overwrote newer files with older files. I don't have any idea why it would do this, except for a serious bug. The file dates and file contents clearly show that new files were overwitten by old versions. I had performed a backup of some of the data before enabling the sync, and the backup confirms the problem. A little more detail: I had previously used BitTorrent Sync on these folders using 1.4.9x. Only 2 computers are using BTSync and they run the Windows 64-bit version. They are on the same wireless network. Relay and tracker servers are turned off for each sync folder. I hadn't run BTSync in over a month. I upgraded BTSync to v1.4.110 on both computers. As part of the BTSync upgrade on System #1 (which had many new files), I selected the option to run BTSync after the program version upgrade. Once it was upgraded and loaded, I ran BTSync on System #2 (which I had already upgraded to the latest version). It than began to sync. Everything looked fine and appeared to run smoothly. But when I checked the files, in many cases, old versions overwote the new versions. I now have to sift through thousands of files to determine the damage BTSync caused and try to rectify as much of the damage as possible. UPDATE: I just had a full-time computer programmer verify all the above facts, and he concluded there is a serious problem with BitTorrent Sync, and that it definitely overwrote NEWER files with OLDER ones in multiple cases. This seems to be a huge problem.