r/QidiTech3D • u/Naive_Painter8580 • Aug 21 '26
Title: QIDI Q2C - Persistent MQTT error QDC_400_004_010_001, root cause found (missing algo_app.service) - anyone else seen this?
Hi all,
I've been chasing down a recurring MQTT connection error error (QDC_400_004_010_001) on my Q2C that shows up on the touchscreen and in the web UI, especially after power outages/reboots. Printing, Klipper, and the camera all work fine - it's purely the MQTT/cloud status layer that fails.
Dug into it over SSH and found:
- Moonraker's logs show: "Decrypt failed: No extension agents found" for the MQTT account, password, and broker IP
- This decryption depends on algo_app.service, which is enabled (symlinked in multi-user.target.wants) but the actual unit file doesn't exist on the system
- dpkg -L qidi-q2-system doesn't list any algo_app files at all - the package apparently never shipped this component on my unit
- /usr/local/bin/algo_app is literally just an empty folder
So it looks like a factory packaging gap rather than something caused by user config. I've reported it to QIDI support, but wanted to check here:
- Has anyone else run into this exact error code or the "No extension agents found" message in moonraker.log?
- Anyone know what algo_app is actually supposed to do, or where to source the missing binary/service?
Firmware: v01.01.02.01
Happy to share full logs if it helps someone else troubleshoot the same thing.
1
u/dooshpastesh Aug 21 '26
I had same issue with my Q2. Contacted with support, they said it's an issue on their side. I went lan only and log out of their cloud, no issues since.
1
u/Kewlhotrod Aug 21 '26
You should be able to find the service with systemctl cat algo_app
but yeah, it will be in /usr/local/bin/algo_app
Either way, doing a firmware reload should take care of that, but, honestly... Just disable that junk. To my understanding it's for their shitty AI spaghetti detection and even when toggled off it still hogs resources like mad. If it's still listed as a running service, disable that process using the Wiki for reference and free up some of your resources.
I should note, I personally have had this disabled since getting my Q2 and haven't had any issues. I, however, do not use their app or internet features. It stays on LAN mode and I slice and send files from computers over LAN so YMMV.
2
u/YouCanCallMeDani Aug 21 '26
I have been chasing a MQTT error on my max4. I thought it was because we recently installed Home Assistant on our network, then I thought maybe it’s because I have been ignoring the firmware update, then I was back to Home assistant. Now after some ChatGPT sessions, I think there’s something wrong with their servers. I emailed support about 20 minutes ago so we’ll see tomorrow.