Problem uploading to board
I don't know if I got the exact error (maybe another sync error), but what helped in my case (in this order, try again every time):


Reinsert the USB cable
Use a different (shorter) USB cable
Put the USB cable in another USB port
Restart the Arduino IDE
Restart the computer
Reinstall the Arduino IDE
Go to device drivers (control panel), check for COM ports, remove Arduino and reinstall