adafruit_support wrote:The board does serial communication via the same FTDI cable?
Yes, successful serial communication is over the same cable that invokes the sync error.
adafruit_support wrote:You might try pressing the reset button at about the time the upload starts (may take a few tries to hit the timing right).
Wow. This eventually worked. I'm getting an upload every three attempts or so, on average. Anyone know if later versions of the Arduino Ethernet will behave less petulantly? These sketches take so long to compile, that three or more upload failures per debugging/testing cycle extends the development time into something approaching impractical.
adafruit_support wrote:What OS are you using?
Windows7 (32- and 64- bit, depending where I physically happen to be).
Anyway, many thanks for getting me moving forward again with this work around.
Hacking is an addiction. Arduino is the gateway drug.