Mcu 'mcu': Unable to connect ender 3V2

Printer Model: ender 3 V2
MCU: ender 3 V2 stock mainboard (creality 4.2.2 mainboard)

I have recently been trying to upgrade my ender 3 V2 to get better print quality, I have installed a creality sprite extruder and CR touch as well as a second Z axis lead screw. I recently have been trying to run klipper firmware so I found a guide (How to Install Klipper on the Ender 3 (With Mainsail OS) | Obico Knowledge Base) and followed all of the instillation steps. I got my raspberry pi model 4B up on wifi and opened up the mainsail web interface and got this error:

mcu ‘mcu’: Unable to connect
Once the underlying issue is corrected, use the
“FIRMWARE_RESTART” command to reset the firmware, reload the
config, and restart the host software.
Error configuring printer

when hitting restart firmware it says this:

Moonraker can’t connect to Klipper!
Please check if the Klipper service is running and klippy_uds_address is correctly configured in the moonraker.conf.

how can I fix this issue?

edit: I got it working! after reinstalling everything I believe the issue was with the makemenuconfig step.
i missed the step that said to select “serial (on USART1 PA10/PA9)”
for anyone else reading this struggling with similar problems, make sure to reread the config file for your printer multiple times to not miss anything

I had the exact same problem a littie while ago, but i cant remember how i fixed it.
I did a search on reddit and found the answer there, I’ll have a look there and get back to you .

I suggest joining the Klipper discord. They’ll be able to help you out the best.

This is where i found my answer sorry i cant find the conversation where they told me how but ask your question here and im sure they will help you, sorry i couldn’t be more help

I suggest to provision a new SD card with Mainsail OS and then use KIAUH to install all relevant items.
Probably easier and faster than searching for the issue.

i reinstalled and updated everything on a fresh install of mainsail but now I’m getting this error:
Unable to open config file /home/pi/printer_data/config/printer.cfg

Once the underlying issue is corrected, use the “RESTART”
command to reload the config and restart the host software.
Printer is halted

Well the error messages should be quite self explaining: You need to provide a proper printer.cfg to the installation.
You could for example follow the guide you already used How to Install Klipper on the Ender 3 (With Mainsail OS) | Obico Knowledge Base and start with Log in to Mainsail OS and configure Klipper for Ender 3

I have the printer.cfg file on the web interface but it says it isn’t on the pi itself.

  1. Download the config you need:

  2. Modify it with your MCU serial

  3. Upload it again as printer.cfg