# Unable to flash Ender3 S1 with Klipper firmware

**URL:** <https://klipper.discourse.group/t/unable-to-flash-ender3-s1-with-klipper-firmware/25645>\
**Category:** General Discussion\
**Created:** [February 17, 2026, 5:10am UTC](https://klipper.discourse.group/t/unable-to-flash-ender3-s1-with-klipper-firmware/25645 "2026-02-17T05:10:12Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![kadim](https://avatars.discourse-cdn.com/v4/letter/k/eb9ed0/32.png) [@kadim](https://klipper.discourse.group/u/kadim)\
**Post date:** [February 17, 2026, 5:10am UTC](https://klipper.discourse.group/t/unable-to-flash-ender3-s1-with-klipper-firmware/25645/1 "2026-02-17T05:10:12Z")

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### Basic Information:

Printer Model: Ender3 S1  
 MCU / Printerboard: STM32F401RCT6  
 Host / SBC: Raspberry Pi 3B+  
 klippy.log [klippy (2).log](https://klipper.discourse.group/uploads/short-url/5iucqBis7NzARzkHIfiHo5NBUpE.log) (905.3 KB)

I’m not able to update my Ender 3 S1 to Klipper Firmware. I have followed the instructions from the top of printer-creality-ender3-s1-2021.cfg but I end up with the printer not being seen by Klipper host.

Things that I’ve tried:

1. I’ve tried both `USB` and `Serial` configuration in `make menuconfig` (BTW can anyone explain me what is the use-case for `USB` option, because I’ve seen some guides mention it, but did not see any justification). I’ve done `make clean` between attempts

 ![image](https://global.discourse-cdn.com/free1/uploads/klipper/original/3X/2/1/2129831c16bebbc76303affb29a9c118cc7e1ff7.png)

1. Restarted both printer and host multiple times, reconnected USB cable, started them in different order
2. Tried the Professional firmware from [Releases · mriscoc/Ender3V2S1 · GitHub](https://github.com/mriscoc/Ender3V2S1/releases) and it worked fine. So I know that my setup is correct (SD card, FAT32, 4096 sector size, STM32F4\_UPDATE folder name and unique file name for the .bin at every attempt). I ended up re-flashing my printer many times and the Professional firmware was successful 3 out of 5 times, but the Klipper firmware flashing failed way over 10 times
3. I can see the USB serial from the host regardless whether I chose `USB` or `Serial` config:

`dk@rpi3b:~/klipper$ lsusb`  
`Bus 001 Device 015: ID 1a86:7523 QinHeng Electronics CH340 serial converter`

`dk@rpi3b:~/klipper$ ls -l /dev/serial/by-id/usb-1a86_USB_Serial-if00-port0`  
`lrwxrwxrwx 1 root root 13 Feb 16 19:05 /dev/serial/by-id/usb-1a86_USB_Serial-if00-port0 → ../../ttyUSB0`

1. I also know that USB cable and Raspberry power are ok, the same hardware had been used before running OctoPi + stock Ender fw over USB

What other things can I try to debug further? Possibly Klipper firmware logs something to one of the UARTs, so I can hook up to it and check the logs? I’ve also seen some posts about re-flashing the whole MCU, including the bootloader with SWD debugger, but it seems those were complete bricks, while mine still recovers to Professional firmware every time.

Maybe someone can send me a working fw .bin to try?

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<div class="post-metadata">

**Author:** ![system](https://global.discourse-cdn.com/free1/uploads/klipper/original/1X/64419bf2aac6639e6ef5cef200dcd456b0a01ac3.png) [@system](https://klipper.discourse.group/u/system)\
**Post date:** [April 18, 2026, 5:11am UTC](https://klipper.discourse.group/t/unable-to-flash-ender3-s1-with-klipper-firmware/25645/2 "2026-04-18T05:11:07Z")

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