Yet another mcu 'mcu': Unable to connect Ender 3 pro

Welcome mesograt, your first post,

I guess, you start with Klipper?

Two ways, I may recommend to understand and find a solution for the problem.

  • Use the “search” function here. I’m very positiv, it was discussed before.
  • YouTube, many people posted about that problem.

Always look here!
https://www.klipper3d.org/Overview.html
https://klipper.discourse.group/t/about-the-knowledge-base-category-table-of-contents

I guess, a new “USB cable”. If right, that’s not your root cause.

You may consider your starting setup. I would recommend another web interface. Mainsail or Fluidd. In my eyes OctoPrint is a generation before, but read about it and make up your mind.

Good luck,
hcet14