I’m experiencing the same issue, suddenly. All with 1.3.94 on OS X 13C64 and 13C1021. Crashing thread always has a backtrace like: Thread 2 Crashed:0 com.googlecode.google-breakpad 0x003066ac google_breakpad::ExceptionHandler::UninstallHandler(bool) + 1901 com.googlecode.google-breakpad 0x00307098 google_breakpad::ExceptionHandler::WaitForMessage(void*) + 4262 libsystem_pthread.dylib 0x95b965fb _pthread_body + 1443 libsystem_pthread.dylib 0x95b96485 _pthread_start + 1304 libsystem_pthread.dylib 0x95b9bcf2 thread_start + 34 Full crash report: http://spo.onl/btsync.crash And I down-revved to 1.3.77 and now I am experiencing the same crash. So it appears to have to do with the content I’m syncing, and not the BTSync version. I’ve now removed all my sync folders from BitTorrent Sync, and started adding them back one by one. I’ve re-added about half of them, and all seems OK for the moment— the crashes have stopped. Unfortunately I am out of time this morning, but I’ll continue later in the day.