# Serial Port Locked

**URL:** <https://discourse.nodered.org/t/serial-port-locked/10655>\
**Category:** General\
**Created:** [29 April 2019 20:11 UTC](https://discourse.nodered.org/t/serial-port-locked/10655 "2019-04-29T20:11:56Z")\
**Posts on this page:** 7\
**Page:** 1

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**Author:** ![tcontrada](https://avatars.discourse-cdn.com/v4/letter/t/f1d935/32.png) [@tcontrada](https://discourse.nodered.org/u/tcontrada)\
**Post date:** [29 April 2019 20:11 UTC](https://discourse.nodered.org/t/serial-port-locked/10655/1 "2019-04-29T20:11:56Z")

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I am running Node Red on a RPi3 and I am having issues with Serial Port Errors in that it indicates:  
**serial port /dev/ttyUSB0 error: Error: Error Resource temporarily unavailable Cannot lock port**

I have NodeJS version 10.15.3

I have tried rebooting and also restarting Node Red.

Any ideas?

Thanks...

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**Author:** ![bakman2](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/bakman2/32/6207_2.png) [@bakman2](https://discourse.nodered.org/u/bakman2)\
**Post date:** [30 April 2019 04:17 UTC](https://discourse.nodered.org/t/serial-port-locked/10655/2 "2019-04-30T04:17:55Z")

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node-red & npm version ?

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**Author:** ![tcontrada](https://avatars.discourse-cdn.com/v4/letter/t/f1d935/32.png) [@tcontrada](https://discourse.nodered.org/u/tcontrada)\
**Post date:** [30 April 2019 13:21 UTC](https://discourse.nodered.org/t/serial-port-locked/10655/3 "2019-04-30T13:21:38Z")

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Node Red 0.20.5  
NPM 6.9.0

Thanks...

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**Author:** ![tcontrada](https://avatars.discourse-cdn.com/v4/letter/t/f1d935/32.png) [@tcontrada](https://discourse.nodered.org/u/tcontrada)\
**Post date:** [1 May 2019 20:47 UTC](https://discourse.nodered.org/t/serial-port-locked/10655/4 "2019-05-01T20:47:47Z")

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I think it might have been related to an Enocean Node. Seems to lock up the port in node red even after a reboot...

Anyone else have an issue with the Enocean node?

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**Author:** ![dudleyjosh](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/dudleyjosh/32/105799_2.png) [@dudleyjosh](https://discourse.nodered.org/u/dudleyjosh)\
**Post date:** [16 May 2019 16:56 UTC](https://discourse.nodered.org/t/serial-port-locked/10655/5 "2019-05-16T16:56:49Z")

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I am experiencing the same "Error Resource temporarily unavailable Cannot lock port" issue. I have several RPi 3's running Protoneer CNC Hats with Node-Red v0.20.5 but I just built a new one yesterday using the latest version of NOOBS and I cannot get the serial port to communicate? Node-Red is using node-red-node-serialport v0.8.1.

When I send a command to the serial port I get no response... if I modify the flow in any way and re-deploy then I get the following error messages:

"serial port /dev/ttyAMA0 error: Error: Port is not open"

"serial port /dev/ttyAMA0 error: Error: Error Resource temporarily unavailable Cannot lock port"

I went so far as to re-install NOOBS and set everything up from scratch a second time and I tried a second Protoneer CNC Hat to make sure it wasn't the issue as well... no luck.

Any ideas?

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**Author:** ![moebius](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/moebius/32/2872_2.png) [@moebius](https://discourse.nodered.org/u/moebius)\
**Post date:** [16 May 2019 17:02 UTC](https://discourse.nodered.org/t/serial-port-locked/10655/6 "2019-05-16T17:02:41Z")

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Did you try the new pi with an sd card of a working one?

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**Author:** ![zenofmud](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/zenofmud/32/316_2.png) [@zenofmud](https://discourse.nodered.org/u/zenofmud)\
**Post date:** [16 May 2019 17:07 UTC](https://discourse.nodered.org/t/serial-port-locked/10655/7 "2019-05-16T17:07:30Z")

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Not at a pi right now, but is it something that needs to be activated in the raspi-config settings?