Sketches not uploading

Hi - I´ve used Arduino Uno for 2 months, it´s worked just fine.

Then, possibly after an update, suddenly sketches do not upload. Being afraid I´d "killed it" I bought a new Uno. And just to test that I uploaded the Blink sketch. Worked fine. Or perhaps it was uploaded already.

Then everytime I power up the Blink runs, but nothing uploads (Tx and Rx dead). And it was probably the same w/ the old board, only there maybe a different sketch was stuck.

And everytime I start the IDE a previous sketch is loaded, instead of an empty.
I run W10/64 and 1.8.10.

N b: The port setting is OK according to the program. I´ve reset several times. I tried it out on another computer, with an older program version (1.8.9) that used to work. Restarted the computers. Uninstalled and reinstalled the program.

Realising two boards or computers can´t be erratic, there must be a software problem.

Kindly help....


Well, I have now. To no avail. Could have been a solution. TX and Rx still dead. No error reports.


have you tried to compil then send an other example (a small skech) ? (other than led..)
when the ide displays "connecting" in red color, what is the error message ?
have you tried to kill the monitor before uploadind ?
the monitor is it ok in the two ways ? pc->uno and uno->pc ??
(i am good with atmega2560+esp8266/ esp8266 alone / esp32, but not in "uno" but i think it's the same..)

This is NOT a clone, both boards are original. But I believe it´s a software issue.

Michel-001 - I already said I tried to upload other sketches and failed, plus the monitor starts w/o an error report. But nothing happens.

I too find it strange.

i am now having the same "will not upload" problems

Download Arduino 1.8.9 and retry.

As said, I´ve done just that on another computer.


Ok, I typed a message in the small window, sent it, and it appeared in the big window… I hope that´s what you meant.
I also get a report in Tools/Get Board Info :

BN: Arduino/Genuino Uno
VID: 0x2341
PID: 0x0043
SN: 7573530353135131F1C0

Also, when sending the Rx and Tx flash. On the new board, on the old one only the Rx flashes and the message doesnt appear


Interesting: Swapping - New 328 on old board: works like w/ the new board - it keeps running Blink but your Tx/Rx trick works.
Old 328 on new board - not working.

They´re both R3, the one you tell me to toast was bought today.

Info for the "old" board:

BN: Arduino/Genuino Uno
VID: 0x2A03
PID: 0x0043
SN: 95530343035351013180


I did nothing out of the ordinary. I do not have a programmer, I was using only basic Arduino StarterKit sketches to be sure.

It all seems to boil down to the problem being either the 328 or the bootloader.
Since the 328 comes at $2 apiece, pls tell me that could be it?
I don´t see how the boards could make a difference if they´re both R3

What did you have plugged into them when this fault started? What pins were used? Have you got a programmer? What sketch were you using? :slight_smile:

If any sort of programmer will help me do a factory reset of the 328 if that´s what´s needed, tell me how to set one up,