Can upload to Nano but not Uno

Hello,
I'm running IDE version 1.8.13 and was uploading sketches to my nano without issue and decided to upload (Blink) to my Uno and received the following error:

avrdude: stk500_getsync() attempt 1 of 10: not in sync: resp=0x16

I tried another Uno and same problem, and both work fine on another machine. Interestingly, when I plug the Nano in, it is assigned to Port 5, while the Uno's get assigned to port 4...all while using the same physical USB port...

I made sure the correct board is selected when changing between the Nano and Uno, and I've tried every suggestion I can find on google to include:

  • Reinstalling drivers
  • Reinstalling IDE
  • Manually assigning a port from the device manager
  • Using the web editor (still same problem)

What could be causing the IDE to upload successfully to the Nano but not the Uno's?

Thank you!

Mr_Laggy:
When I plug the Nano in, it is assigned to Port 5, while the Uno's get assigned to port 4...all while using the same physical USB port...

The physical USB port doesn't matter. If you connect your Nano to any USB, then it will always give same fixed COM port. And if you connect UNO to any USB port, then it will also give the same fixed COM port.

If your UNO is giving such error, then you should burn it's bootloader first and then try to upload the sketch. You will need your other Nano for that. You can google "How to burn Arduino UNO bootloader with Nano" and you will find the tutorials.

..Arnav

@ArnavPawarAA

If the boards work fine on another PC, I have serious doubts that it is the boot loader.

@Mr_Laggy
1)
Which operating system?
2)
Did the Unos ever work on this specific system with this specific IDE (or an older one)?
3)
Which operating system and IDE version on the other PC where it all works?
4)
This post by ballscrewbob has (additional) cleanup instruction for a re-install.
5)
After (4), try another version; newer is not always better.

sterretje:
Which operating system?

@sterretje The OP is referring to a port name starting with COM. So obviously, the OS is Windows. If the OP was using any other OS, then the port name would be like "dev/tty"

..Arnav

ArnavPawarAA:
@sterretje The OP is referring to a port name starting with COM.

Where?

Thank you for the feedback. I took both Uno's back to the "other machine" where they worked before...and now they both have the same problem....?! One Uno is a standard Rev3 and the other is an Uno Wifi.

sterretje:
@ArnavPawarAA

If the boards work fine on another PC, I have serious doubts that it is the boot loader.

@Mr_Laggy
1)
Which operating system?
2)
Did the Unos ever work on this specific system with this specific IDE (or an older one)?
3)
Which operating system and IDE version on the other PC where it all works?
4)
This post by ballscrewbob has (additional) cleanup instruction for a re-install.
5)
After (4), try another version; newer is not always better.

  1. Windows 10
  2. Yes, they both worked on this machine, same IDE version (most current)
  3. Windows 10 as well
  4. Great article. Followed it exactly but still same results
  5. I installed 1.8.12. Same results
  • I'll burn new bootloaders...might as well at this point.

TheMemberFormerlyKnownAsAWOL:
Where?

OP mentioned Device Manager, so @ArnavPawarAA was right that it was Windows. My bad.

Ok, so why exactly can a perfectly good UNO all of a sudden require a bootloader burn?? I got one Uno working but the other one (Uno Wifi R2) doesn't want to cooperate. Can someone shed light on what corrupts a bootloader? I'm literally over here only blinking led's so I don't know why this happened or how to prevent it in the future.

Thank you!

The Uno WiFi R2 is not an Uno. If you tried to burn the Uno boot loader in it, it will be the reason why it does not want to cooperate.

I can't tell you why boot loaders get corrupted.

sterretje:
OP mentioned Device Manager, so @ArnavPawarAA was right that it was Windows. My bad.

No problem freind.

You didn’t try to set the board type to “Uno” for your Uno WiFi 2, did you? (Or vis versa)
They’re completely different cpus - the wifi2 doesn’t even use a bootloader!
(Horrible naming job. Sigh.)