avrdude: ser_open(): can't open device "\\.\COM3": Access is denied.

The usual culprit is a mobile phone / PDA application running in the background that constantly probes for a connected device.

Not sure if this will help anyone else, but with the 3d printer kit I purchased it had me install the Repetier Software which has a server and host component. The server was constantly connecting to the arduino and preventing me from being able to upload.

I was able to

  • End Process in task manager for avrdude.exe
  • Disable the com port to the arduino in device manager (triple low beep)
  • Enable com port to the arduino in device manager (low/high beep). Upload was successful and stable.

As always, verify Arduino IDE|Tools|Board: and Port: are correctly selected (my board changed once, port becomes deselected occasionally)

If you go to C:\Program Files (x86)\Arduino\hardware\tools\avr\bin and can't delete avrdude.exe then it is probably still running and the process needs to be ended - I learned this by trying to delete the Arduino folder (to reinstall) but was unsuccessful because this program was still running.

This has been massively frustrating - Upon Sketch|Upload the avrdude.exe program should be killed automatically.

Thank You, it solved my problem. Arduino Mega 2560

terry777: solution!!!! 1. device manager 2. select ports 3. select port of arduino board examle : com1 ... com3 whatever it is 4. right click on com. 5. select properties 6. tab- port settings 7. click advanced 8. com port number- select new port number that is not in use. 9. confirm.. save and continue

the problem is a conflict between hardware devices, ie. the port is now used by another hardware device, mouse, ect..

Same problem here. I just needed to disconnect the RX and TX on D0 and D1 and it works. I just wanted to provide my feedback on this. I was looking for this too.

I'm having a similar problem I'm trying to upload to, what I believe is a Chinese fake UNO R3. Under tools the port option is visible but unavailable and I'm getting ( avrdude: ser_open(): can't open device "\.\COM3": The system cannot find the file specified. ) for an error message. any advice would be great.

Actually agcsoft's link to the Chinese drivers was exactly what I needed Thanks a ton.

I encountered this error and something close to the error as in the following URL: https://forum.arduino.cc/index.php?topic=28223.30 While my Uno was connected to pins tx and rx and while connected I tried to upload a sketch.

The assumed reason for it is the fact that these pins are able to load a bootloader to the Arduino and if they are connected, the board expects to be loaded with a bootloader.

I've just had this same issue. Tried lots of the solutions above but the fix for me was unplugging a MTB GPS device that was on connected to my PC via USB. As soon as I unplugged that device everything worked fine.

avrdude: ser_open(): can't open device "\.\COM3": Access is denied.

I tried all the solutions but none of them worked

TraumaER: Not sure if this will help anyone else, but with the 3d printer kit I purchased it had me install the Repetier Software which has a server and host component. The server was constantly connecting to the arduino and preventing me from being able to upload.

Thank you for your help !!! It was the guilty

I used Repetier server for long time, now I use Cura...

Thank because I was downcast. For others maybe you have a software like it.

[quote author=Coding Badly link=msg=3108711 date=1485801707] The usual culprit is a mobile phone / PDA application running in the background that constantly probes for a connected device.

[/quote] I concur. I started with a new W7 64b prof computer, installed all drivers as they should be and were on the previous computers, yet same error as OP. i tried almost every trick described in the fora to no avail.

Until I found this comment. My mobile phone was indeed plugged in a USB socket. Removing it solved the issue.

EDIT: after removing the phone, uploading once (which gave no issue) and the reconnecting the phone on USB gave no further issues.

my was same problem yar

i just the change com pin also but it shows same error

my also showing same error and i try which u guys told but showing the same erro

TraumaER: Not sure if this will help anyone else, but with the 3d printer kit I purchased it had me install the Repetier Software which has a server and host component. The server was constantly connecting to the arduino and preventing me from being able to upload.

Dude, thank you! That was my issue too ! I opened the repetier-host application and did 'server->stop local server'.

I just wanted to add something that worked for me: I turned on verbose output for upload, noticed it was overriding baud rate. I manually set the arduino baud rate to that desired baud rate in device manager and the upload then worked fine.

J'ai connu ce problème. Il n' y a qu'une seule façon de le résoudre: Supprimer Arduino relancer l'ordi réinstaller Arduino. Cordialement François

There are LOTS of different reasons why this could happen. So, I thought I’d share one other possibility, which was the solution in my case:

I was developing my project on a barebone AtMega328p (chip in breadboard), and had worked on it for days, without problems. Then all of a sudden it throws the error message in question.
Turns out the boot loader was messed up. Burned a new boot loader, and got right back on track.

This could of course happen to any Arduino as well, not only the barebone setup that I was working on.

nivesh: Hi, i just purchased an ezlcd 303 with Uno on it. There is no respond and handshake during test on Termie (code like CLS, PING) despite COM port, baud rate has been checked.

For IDE test i get the following error: avrdude: ser_open(): can't open device "\.\COM3": Access is denied.

Thanks.

Chances are that your COM port is busy. Just detach any device that may be using it.

RomeoDelta:
In my case, none of this worked. Turns out the problem was that Windows Update for Win10 “updated” my USB host controller and the new driver malfunctioned, but only in a few specific cases, the use of an Arduino Uno being one of them. The fix was to uninstall the driver and reinstall the manufacturer-supplied driver. Just one more thing to look at in the event you have this issue.

RD7

This worked for me. Go to the device manager and look for the device under “Ports”. Right-click and uninstall the device and it will disappear. Then unplug the device and try again. It may tell you to restart your computer first. I have multiple USB ports that I use and I had to uninstall it for each one. Then once you plug back in, it installs the latest driver. You can also check sparkfun or similar for the latest drivers for either CH340 or the other FTDI chips.