Random freeze during printing – KlipperScreen unresponsive, cannot access Mainsail

General Discussion
1

Basic Information:

Printer Model: 1000x1000x1000mm i diy
MCU / Printerboard: mks monster 8 v2.0
Host / SBC
klippy.log

moonraker.log (76.8 KB)

Describe your issue:

Hi everyone,

I’m experiencing a random and hard-to-diagnose issue with Klipper and would appreciate any help or guidance.

  1. The printer stops in the middle of a print
  2. KlipperScreen freezes and the touchscreen becomes unresponsive
  3. Web interface (Mainsail/Fluidd) is not accessible
  4. SSH connection also fails
  5. No clear error message is shown on the screen

Behavior:

  1. Happens completely at random

  2. Sometimes the printer runs fine for up to 10 hours

  3. Sometimes it freezes within 5 minutes after starting a print

  4. Not related to a specific G-code file (tested multiple files)

  5. Mainboard: mks monster8 v2.0

  6. SBC: rbpi 3B+

  7. Touchscreen running KlipperScreen

  8. Web interface: Mainsail

What I have tried so far:

  • Checked power supply for the rpbpi

  • Replaced USB cable

  • Reduced print speed

  • Checked CPU temperature (not overheating)
    → The issue still occurs

  • Has anyone experienced a complete system freeze like this (screen + web + SSH)?

Please let me know what logs or additional information I should provide to help diagnose this.
Any advice would be greatly appreciated.

Thank you :folded_hands:

4

Please add, as formerly requested, the klippy.log to your next post.

5

klippy (2).log (3.6 MB)
Sorry, I forgot to attach the klippy.log file in my previous post.

I have also tried reinstalling Klipper from scratch (fresh install), but the problem still happens.
The printer continues to stop randomly while printing — sometimes after around 10 hours, sometimes just 5 minutes after starting a print.

I would also like to ask if Obico could be the cause of this issue.
I am using a Logitech Brio 100 camera, and my crowsnest settings are:

  • Resolution: 640x480

  • Max FPS: 15

Could Obico or the camera streaming be causing the random freezes or disconnects?
Updates since the initial post:

  1. I replaced the USB cable between the SBC and the MCU with a thicker, higher-quality cable that supports higher data transfer speeds.

  2. I added a dedicated Mean Well 5V 5A power supply for the Raspberry Pi.

6

Hi everyone,
I just wanted to share an update because I believe I have found the root cause of this issue.

After checking my klippy.log, I noticed that right before the freeze there is a long sequence of nulnulnulnul... and then the log suddenly stops. After that, the whole system resets. This confirms that the SBC is crashing, not just Klipper.

I followed the troubleshooting steps from this post:
https://klipper.discourse.group/t/help-klipper-crashes-mid-print/24434/44

After applying those changes and fixing the root cause, my printer has now been running continuously for 4 days without any freezes, disconnects, or crashes.
KlipperScreen remains responsive and Mainsail stays connected the entire time.

So in my case, the issue was not a Klipper configuration problem, but a system-level crash on the host.

Hopefully this helps anyone else who is seeing random freezes with an unresponsive screen and no web access.