avrdude: verification error, first mismatch at byte 0x0002
0x42 != 0x83
avrdude: verification error; content mismatch
if anyone has a clue as to what this means, could you please let me know. I can no longer upload sketches to my UNO. It still has the last sketch on it, but will only run the setup.
With virtually no other context, I think it means that 42 does not equal 83.
Well assume in the context of a failed upload. At least that is how I took the question.
Lefty
Look on the bright side - the first two bytes verified OK.
I believe that verification happens after avrdude reads the flash content from the microcontroller; it's verifying that what was written to the microcontroller matches the *.hex file that was uploaded. Probably an uploading problem, though I don't have any suggestions for fixing it; some people have found switching computers helps.
first of all, LOL!!!!! you guys are too funny man 
why it should think that 42 was ever equal to 83, I will never know.
I don't think this little guy is gonna make it back 
it won't accept any new sketches to be uploaded and it won't run the commands in the current sketch.
second of all, I think I killed my 'duino. I was reviewing the circumstances that led to this situation and I think that it may have experienced a short to a power terminal off a board I was working. Which, if I'm right, sent about 5A back up pin 10. I've got another UNO in the mail already and a new ATMEGA328. I'm gonna try to replace it at some point. So in the short run I'm sad that I've lost my first Arduino, but I'm happy too because with luck, when all's said and done, I'll have two Arduinos.
avrdude: verification error, first mismatch at byte 0x0002
0x42 != 0x83
avrdude: verification error; content mismatch
why it should think that 42 was ever equal to 83, I will never know.
I hope you guys are kidding, but in case you are not.... during the verification (mentioned in reply #4) the hex file had one of those numbers and the Arduino memory had the other. They should be the same but they are not, hence the verification failed.
Don
Excuse me.This isn´t a reply; it´s just that I get the same erro mess. That means message!
As far as I understand, I don´t need the bootloader; I can upload sketches WITHOUT it.
So I tried with an ATtiny45, my parallel port programmer and the BLINK sketch.
Mess:
Wrong MCU found. Did you select...?
AVR device not responding
Initialization failed rc=-1
Invalid device signature
Expected signature is 1E 92 06
Veriification error first mismatch at byte 0x0000
0x20 !=0xff
verification error content mismatch.
Any ideas? Thanks
Unfortunately, I never did find a way to fix that particular problem with my board. I ended up putting a new ATMega 328 onto the board and that seemed to fix everything up for me.
If you're uploading something with avrdude (especially bootstraping) then it could mean that you haven't unlocked the chip before attempting to write.