Hello Bill,
This is only applicable if you have a petty old board, the new 1.2.20 firmware (and all firmwares up) are restricted to uhex bootloader only (which is applied standard in boards since 2011-03), firmware release will from now on only be released in uhex format.
But this requires users of older boards to upgrade their bootloader if applicable (and they want to run the latest firmware). Checking of bootloader version in your board is easy: In VemsTune -> File -> Firmware info -> SerialNumber; If this starts with "v3.3_u" you have uhex bootloader (good) if it stats with "v3.3_n" you have non-hex bootloader (requires upgrade).
Best regards, Dave