# Help! USB serial port randomly disappeared for no apparent reason!

**URL:** <https://discourse.nodered.org/t/help-usb-serial-port-randomly-disappeared-for-no-apparent-reason/94975>\
**Category:** General\
**Created:** [29 January 2025 06:40 UTC](https://discourse.nodered.org/t/help-usb-serial-port-randomly-disappeared-for-no-apparent-reason/94975 "2025-01-29T06:40:40Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![Roaders](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/roaders/32/11282_2.png) [@Roaders](https://discourse.nodered.org/u/Roaders)\
**Post date:** [29 January 2025 06:40 UTC](https://discourse.nodered.org/t/help-usb-serial-port-randomly-disappeared-for-no-apparent-reason/94975/1 "2025-01-29T06:40:40Z")

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Hi All

I have a raspberry pi running remotely that for over a year has been logging data received over a USB serial port. Node-red takes this data and passes it to a database.

All of a sudden this has stopped working....

Nothing has really changed recently... Except I had an issue where I was getting errors to do with a disk being full...  
The disk wasn't really full, the network location that the pi was trying to write logs to has been turned off so that broke a load of stuff. I've now removed references to that network location and removed the mount details.

I can't understand why this device has suddenly gone after working for so long. As I said I am remote so don't have physical access to it but I can get people to go and prod it. Someone has already gone to make sure that the usb cable is still plugged in.

Any help very much appreciated.

In the node red logs I see:

> [@](#):
>
> [error] [serialconfig:064dbcc85c43b2be] serial port /dev/ttyUSB0 error: Error: Error: No such file or directory, cannot open /dev/ttyUSB0

if I do lsusb I see:

> [@](#):
>
> Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub  
> Bus 001 Device 002: ID 2109:3431 VIA Labs, Inc. Hub  
> Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

and if I do dmesg -w I find some mentions of USB stuff:

> [@](#):
>
> [1.838994] usb 1-1: new high-speed USB device number 2 using xhci\_hcd  
> [1.839328] Run /sbin/init as init process  
> [1.839342] with arguments:  
> [1.839351] /sbin/init  
> [1.839361] splash  
> [1.839370] with environment:  
> [1.839379] HOME=/  
> [1.839388] TERM=linux  
> [1.989570] usb 1-1: New USB device found, idVendor=2109, idProduct=3431, bcdDevice= 4.21  
> [1.989608] usb 1-1: New USB device strings: Mfr=0, Product=1, SerialNumber=0  
> [1.989623] usb 1-1: Product: USB2.0 Hub  
> [1.991642] hub 1-1:1.0: USB hub found  
> [1.991883] hub 1-1:1.0: 4 ports detected

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**Author:** ![ziga](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/ziga/32/98138_2.png) [@ziga](https://discourse.nodered.org/u/ziga)\
**Post date:** [29 January 2025 06:55 UTC](https://discourse.nodered.org/t/help-usb-serial-port-randomly-disappeared-for-no-apparent-reason/94975/2 "2025-01-29T06:55:32Z")

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Not really NR related so you'd better be off asking this on R PI or stackexchange forums...

> [@Roaders](#):
>
> I've now removed references to that network location and removed the mount details.

... but you might unmounted your USB drive also? If so:

> **[Raspberry Pi Mount a USB Drive Tutorial](https://pimylifeup.com/raspberry-pi-mount-usb-drive/)**
>
> How to mount a USB drive to the Pi.

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**Author:** ![Colin](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/colin/32/17040_2.png) [@Colin](https://discourse.nodered.org/u/Colin)\
**Post date:** [29 January 2025 10:28 UTC](https://discourse.nodered.org/t/help-usb-serial-port-randomly-disappeared-for-no-apparent-reason/94975/3 "2025-01-29T10:28:29Z")

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Since `lsusb` is not showing the device then that suggests that it (or the port) is broken.

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**Author:** ![dceejay](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/dceejay/32/38_2.png) [@dceejay](https://discourse.nodered.org/u/dceejay)\
**Post date:** [29 January 2025 14:27 UTC](https://discourse.nodered.org/t/help-usb-serial-port-randomly-disappeared-for-no-apparent-reason/94975/4 "2025-01-29T14:27:50Z")

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Also if you have been continuously writing logs files to the SD card you may want to check the integrity of it as it may be starting to fail / losing miscellaneous files.

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**Author:** ![edje11](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/edje11/32/572_2.png) [@edje11](https://discourse.nodered.org/u/edje11)\
**Post date:** [29 January 2025 19:02 UTC](https://discourse.nodered.org/t/help-usb-serial-port-randomly-disappeared-for-no-apparent-reason/94975/5 "2025-01-29T19:02:15Z")

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and check your power supply. Maybe it can't delivery the request power anymore due the capacitors that loses capacity by ageing.

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**Author:** ![system](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/1X/d073cd938eafa2e558d7c2cd59003b3ef4963033.png) [@system](https://discourse.nodered.org/u/system)\
**Post date:** [29 April 2025 19:03 UTC](https://discourse.nodered.org/t/help-usb-serial-port-randomly-disappeared-for-no-apparent-reason/94975/6 "2025-04-29T19:03:12Z")

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