I thougt it maybe is that way because of this line in the log:
Args: ['/home/biqu/klipper/klippy/klippy.py', '/home/biqu/printer_data/config/printer.cfg', '-I', '/home/biqu/printer_data/comms/klippy.serial', '-l', '/home/biqu/printer_data/logs/klippy.log', '-a', '/home/biqu/printer_data/comms/klippy.sock']
Yeaa, at the first of begining of my machines, i used CM1 and OS from biqu for the cm1, and user was biqu. Even now i use cm4 and mainsailOS, i have kept using biqu as user as i made a lot of things under biqu user. maybe in the future i’ll change this.
I had the same problem with both of my printers, which both run on a Raspberry Pi 3. I solved this by adjusting a timing setting in the Linux OS (using Putty), although I have to re-apply this after every Klipper update:
grep “TRSYNC_TIMEOUT =” ~/klipper/klippy/mcu.py
sed -i ‘s/TRSYNC_TIMEOUT = [0-9.]*$/TRSYNC_TIMEOUT = 0.05/’ ~/klipper/klippy/mcu.py
sudo systemctl restart klipper
I run a DIY toolchanger(allso with a MantaM8P), and that adds allot of MCU’s, one for each toolhead, and I have 6… I allso fought the TTC plague, somethimes even when just idling and not even homed. I got rid of all those TTC by just changing the SD card. I got a bach of Intenso sd cards that just did not work ok. Some of them just died mid print. Now i have a CM4 with 32G MMC and no more TTC. So… check your SD card.
Haha, I wish I could blame the storage too. 
I’m actually running a Compute Module 4 with a 32 GB eMMC, so it’s not an SD card in my case. (I guess)
That said, it is true that this issue is extremely random. It almost never happens. The printer can run perfectly fine for days, and then one day, completely out of nowhere, it happens once. That’s what’s making it so difficult to track down. I’m still leaning towards some software/service issue or maybe something odd in my installation, but I honestly don’t know yet. I’ll keep digging. Thanks for the suggestion!
@hardy8, it is not related to the topic or TTC.
It is a duct tape for homing timeout ONLY.
@printicus, if you have issues, you can create your own topic and share the log.
There is some work going on to make Klippy more robust against IO (slow sdcard for example) issues: RFC: Reactor - IO threads by nefelim4ag · Pull Request #7230 · Klipper3d/klipper · GitHub
-Timofey
No issues, just adding the SD card as a couse of TTC issues… My rig works great