When updating the firmware to Marlin using Arduino 1.3.5 I get a bunch of “avrdude: stk500_getsync() attempt 7 of 10: not in sync: resp=0x02” errors. The correct board and serial COM options are selected. Windows also says that the COM drivers are up to date.

It seems to compiles fine, just not upload to the printer. Any idea what might be causing the error?