# Avrdude: ser\_open(): can't open device "\\.\\COM3": **URL:** \ **Category:** Uploading\ **Created:** [April 2, 2025, 4:20pm UTC](https://forum.arduino.cc/t/avrdude-ser-open-cant-open-device-com3/1369964 "2025-04-02T16:20:13Z")\ **Posts on this page:** 12\ **Page:** 1
**Author:** ![mutmong](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/mutmong/32/1127277_2.png) [@mutmong](https://forum.arduino.cc/u/mutmong)\ **Post date:** [April 2, 2025, 4:20pm UTC](https://forum.arduino.cc/t/avrdude-ser-open-cant-open-device-com3/1369964/1 "2025-04-02T16:20:13Z")
> [@Sketches not uploading on Arduino Nano frowning](https://forum.arduino.cc/t/sketches-not-uploading-on-arduino-nano/1367375/1): > > I've already tried changing the port and the bootloader but nothing has fixed it. ...and i have a similar problem with my R3 nano clone. Also tried other bootloader. Can't change port because IDE does not detect a Arduino board. Only the standard blinking sketch with blinking L led but no connection to upload (and yes pc detects a device). _Sketch uses 2034 bytes (6%) of program storage space. Maximum is 30720 bytes._ _Global variables use 188 bytes (9%) of dynamic memory, leaving 1860 bytes for local variables. Maximum is 2048 bytes._ _avrdude: ser\_open(): can't open device "\.\COM3": Het systeem kan het opgegeven bestand niet vinden._ _Failed uploading: uploading error: exit status 1_ I also have a normal size R3 and this one works perfect. thx! ---
**Author:** ![sterretje](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/sterretje/32/391294_2.png) [@sterretje](https://forum.arduino.cc/u/sterretje)\ **Post date:** [April 3, 2025, 3:34am UTC](https://forum.arduino.cc/t/avrdude-ser-open-cant-open-device-com3/1369964/2 "2025-04-03T03:34:39Z")
Your question has been split from an existing topic. Please do not hijack topics; especially if the error is different. ---
**Author:** ![ledsyn](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/ledsyn/32/1203827_2.png) [@ledsyn](https://forum.arduino.cc/u/ledsyn)\ **Post date:** [April 3, 2025, 4:42am UTC](https://forum.arduino.cc/t/avrdude-ser-open-cant-open-device-com3/1369964/3 "2025-04-03T04:42:59Z")
> [@mutmong](#): > > R3 nano clone There's a hint already there. > [@mutmong](#): > > Also tried other bootloader. Here we go, shooting blindly in the forest hoping to hit a deer. > [@mutmong](#): > > Can't change port because IDE does not detect a Arduino board. Now we're getting somewhere. You still believe in the bootloader being at fault, if you even can't upload anything? You likely have a driver issue. What serial chip is present on your Nano clone? ---
**Author:** ![mutmong](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/mutmong/32/1127277_2.png) [@mutmong](https://forum.arduino.cc/u/mutmong)\ **Post date:** [April 3, 2025, 5:58am UTC](https://forum.arduino.cc/t/avrdude-ser-open-cant-open-device-com3/1369964/4 "2025-04-03T05:58:20Z")
Now if i stick the Nano in the pc via usb no more blinking L led. But: pc and IDE see there is a device connected but IDE can't upload sketch (sorry don't have pc with me to show error). I removed the ch340 driver (i should be this one because the board is with the ch340 usb chip) ans installed the (older) friver from the Sparkfun website. No succes ---
**Author:** ![ledsyn](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/ledsyn/32/1203827_2.png) [@ledsyn](https://forum.arduino.cc/u/ledsyn)\ **Post date:** [April 3, 2025, 6:04am UTC](https://forum.arduino.cc/t/avrdude-ser-open-cant-open-device-com3/1369964/5 "2025-04-03T06:04:39Z")
What does device manager say about it, when you plug it in? (A refresh of the view might be necessary) ---
**Author:** ![mutmong](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/mutmong/32/1127277_2.png) [@mutmong](https://forum.arduino.cc/u/mutmong)\ **Post date:** [April 3, 2025, 6:11am UTC](https://forum.arduino.cc/t/avrdude-ser-open-cant-open-device-com3/1369964/6 "2025-04-03T06:11:51Z")
Device manager sees the 'ch340' device without errors ---
**Author:** ![ledsyn](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/ledsyn/32/1203827_2.png) [@ledsyn](https://forum.arduino.cc/u/ledsyn)\ **Post date:** [April 3, 2025, 6:25am UTC](https://forum.arduino.cc/t/avrdude-ser-open-cant-open-device-com3/1369964/7 "2025-04-03T06:25:19Z")
Can this COM port be selected in the IDE too? ---
**Author:** ![mutmong](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/mutmong/32/1127277_2.png) [@mutmong](https://forum.arduino.cc/u/mutmong)\ **Post date:** [April 3, 2025, 6:28am UTC](https://forum.arduino.cc/t/avrdude-ser-open-cant-open-device-com3/1369964/8 "2025-04-03T06:28:40Z")
Although i can set the right com port now (and select nano in IDE) the tx and rx led's don't start flickering when the IDE starts uploading sketch to board (it just keeps uploading without result). I'll try some other stuff i read i could remedy the problem but i'm not at home now. -removing ch340 driver without re install and plugging nano in so new driver get's installed automaticly -try other USB cable -plug board in to other usb port -... -buying a Sparkfun or Seeed Nano board 😡 ---
**Author:** ![ledsyn](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/ledsyn/32/1203827_2.png) [@ledsyn](https://forum.arduino.cc/u/ledsyn)\ **Post date:** [April 3, 2025, 6:59am UTC](https://forum.arduino.cc/t/avrdude-ser-open-cant-open-device-com3/1369964/9 "2025-04-03T06:59:35Z")
> [@mutmong](#): > > -removing ch340 driver without re install and plugging nano in so new driver get's installed automaticly Never heard of anyone having success with the latest driver. > [@](#): > > -try other USB cable If Windows finds and detect, I don't think this is causing your problem. > [@mutmong](#): > > -plug board in to other usb port You can always try, but see above. Using another computer would be more interesting. ---
**Author:** ![horace](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/horace/32/1014299_2.png) [@horace](https://forum.arduino.cc/u/horace)\ **Post date:** [April 3, 2025, 7:43am UTC](https://forum.arduino.cc/t/avrdude-ser-open-cant-open-device-com3/1369964/10 "2025-04-03T07:43:25Z")
after using multiple COM ports (sometimes end up with thirty or forty COM ports) I find I have to uninstall the COM ports to make a device work 1. open Device manager and expand Ports COM & LPT) 2. click _View \> Show Hidden Device_s – you get list such as 3. right click on each COM port - click _Uninstall Device_ – click _Uninstall_ button 4. when complete plug in your device and hopefully the COM port should appear ---
**Author:** ![mutmong](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/mutmong/32/1127277_2.png) [@mutmong](https://forum.arduino.cc/u/mutmong)\ **Post date:** [April 3, 2025, 4:13pm UTC](https://forum.arduino.cc/t/avrdude-ser-open-cant-open-device-com3/1369964/11 "2025-04-03T16:13:33Z")
Finaly solved. Bit suspicious because the standard installed blink sketch did not work anymore (bootloader bricked?). First tried other usb ports (and erasing). Then other usb cable. Then uninstalling and re-installing the ch340 driver (this time the widows/microsoft version) and aha...IDE recognizes port AND nano board automatically. but...still won't upload sketch. Then grabbed my uno and used it again as programmer and...voila, bootloader re-installed So this time it works. Cause??? Then tried uploading sketch in nano with success! thx everybody! ...everything points at a faulty bootloader but it's a mystery why re-loading the bootloader did not work yesterday. ---
**Author:** ![system](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/system/32/1140315_2.png) [@system](https://forum.arduino.cc/u/system)\ **Post date:** [September 30, 2025, 4:14pm UTC](https://forum.arduino.cc/t/avrdude-ser-open-cant-open-device-com3/1369964/12 "2025-09-30T16:14:26Z")
Closed on September 30, 2025, 4:14pm UTC This topic was automatically closed 180 days after the last reply. New replies are no longer allowed.