I ran into this same problem today and I found a solution and came to the forums to register to share it. For me, I was trying to sync from a linux box to windows and one final file would not sync. It was 73.7KB. I went to the root dir on the linux box and searched for a file of that size. -R is for recursive searching, -h is for human readable file sizes (74K, 244M, etc) ls -laRh | grep ' 74K' -rw-r--r-- 1 pi pi 74K May 24 20:02 Ron Paul on the boston bombing and military response.jpg -rw-r--r-- 1 pi pi 74K May 4 03:51 ron paul on the boston bombing and military response.jpg based on the results, you can see that I had two files that were different in linux (case sensitive), but the same in windows (not case sensitive). I deleted the duplicate file on the linux box (or change the name if they aren't dups) and then everything was fine. Look for weird characters in the filename or duplicate names based on the OS.