# Klipper not connecting to the MCU

**URL:** <https://klipper.discourse.group/t/klipper-not-connecting-to-the-mcu/8908>\
**Category:** General Discussion\
**Created:** [June 11, 2023, 2:23am UTC](https://klipper.discourse.group/t/klipper-not-connecting-to-the-mcu/8908 "2023-06-11T02:23:49Z")\
**Posts on this page:** 1\
**Showing post:** 4

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**Author:** ![Sineos](https://yyz2.discourse-cdn.com/free1/user_avatar/klipper.discourse.group/sineos/32/18_2.png) [@Sineos](https://klipper.discourse.group/u/Sineos)\
**Post date:** [June 11, 2023, 9:43am UTC](https://klipper.discourse.group/t/klipper-not-connecting-to-the-mcu/8908/4 "2023-06-11T09:43:25Z")

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> [@Debian Bullseye Bug causing Klipper to no longer find the printer board](https://klipper.discourse.group/t/debian-bullseye-bug-causing-klipper-to-no-longer-find-the-printer-board/8231/1):
>
> - Execute `sudo apt edit-sources`
> - In the editor that opens (if asked choose `nano`) add following line at the end:
> 
> ```auto
> deb http://ftp.debian.org/debian bullseye-backports main non-free contrib
> 
> ```
> 
> - Save and close
> - Run: `sudo apt update`
> - Closely monitor the output of the above command. On errors see the following post
> - Run: `sudo apt install udev -t bullseye-backports`
> - Reboot

What is missing? Does not look too complicated to follow these few steps,no?

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