Avrdude: ser_open(): can't set com-state for "\\.\COM6"

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Hi. I have been trying to use my Arduino Uno for a while but every time I try to upload a sketch, it gives the following error: avrdude: ser_open(): can't set com-state for "\.\COM6". I'm running a windows 11 latest version Dell pc. Before (just yesterday) it was working perfectly fine; now it's giving an error. I've tried using different pcs/desktops, different USB cables, uninstalling and reinstalling drivers and the device from device manager but nothing is working. I even installed the IDE and tried using both IDE 2.0 and the 1.8.19 but it still doesn't work. The only place it's uploading is on a school windows 10 desktop that's very slow. I would appreciate any help. Thank you.

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NVM. It was a driver issue and is working now.

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Hi @detectiveak68. I'm glad it is working now.

Would you mind sharing some details about what the driver issue was and how you were able to solve it? I ask because I see users periodically reporting this error and I would like to be able to provide assistance with fixing it but I'm not sure what the cause is or what the procedure is for solving it.

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Of Course! I'm not sure if my Arduino is a genuine arduino or a clone. I didn't know about this at the time and just got it off amazon. It uses the CH340 driver. So, after I got this error, I was very confused. I thought this might be a driver error so I tried to reinstall the driver from the official site. It still didn't work. So, I just searched CH340 driver and clicked on the first link that I saw (CH340 Drivers for Windows, Mac and Linux). I downloaded the zip file and ran the exe and it said that a newer version was already installed. I thought that maybe the newer version was the problem and said yes to replace the new with the old. After it was done I ran the blink sketch again and somehow it worked! Not really sure how, but I'm happy all the same. Hope that helps!

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Thanks for the details! That information is very useful to me.

There has a been a recent spike of reports of odd errors related to the ports of boards using the CH340 USB chip.

The information in this post indicates it was related to a Windows update that updated the CH340 driver:

There are several reports of people solving the problem by installing drivers obtained from various 3rd party sources as you did. Since I am reluctanct to advise users to install drivers obtained from any source other than the chip manufacturer (WCH in this case), I suggested an alternative approach of using Windows Device Manager to do an uninstall/reinstall cycle of the device:

https://forum.arduino.cc/t/rewrite-bootload-to-arduino-nano/1128466/8

I have not been able to reproduce the fault even though I do have the problematic driver version 3.8.2023.2 installed on my computer so I can't personally verify that fix, but so far both the users who followed the instructions reported it fixed the error.

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I attempted to fix this problem using Windows Device Manager. I was able to successfully uninstall the device and the driver. When I reconnected my Arduino Uno R3 the same driver installed (ver. 3.8.2023.2) and I was unable to upload and got the same error.

I found an older driver on the Sparkfun site How to Install CH340 Drivers - SparkFun Learn
and installing that driver solved the problem. The driver that installed and worked is ver. 3.4.2014.8 dated 8/8/2014.

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