libgpiod v2 repeatedly prints "Lost access to message queue" during normal GPIO reads on Raspberry Pi OS (Bookworm/Trixie)

[glennoky]

On Raspberry Pi OS (Bookworm/Trixie), libgpiod v2 prints the message "Lost access to message queue" to stderr during normal, successful GPIO operations.
This occurs even when the GPIO line is functioning correctly and the application is reading valid data.
The message appears to be debug‑level noise rather than an actual error, but it is emitted unconditionally and bypasses Python’s stderr redirection, making it difficult to suppress.

Environment
• Hardware: Raspberry Pi 4B
• OS: Raspberry Pi OS Bookworm (Debian 12 base)
• Kernel: Linux 6.12.75 (default Pi OS kernel)
• libgpiod version: v2.2.1 (from Raspberry Pi OS repositories)
• Language: Python 3.13.5
• Library using libgpiod: Adafruit CircuitPython DHT (which uses libgpiod v2 internally)

Minimal Reproduction
Python script:
import adafruit_dht
import board
dht = adafruit_dht.DHT22(board.D17)
print("Temp:", dht.temperature)
print("Hum:", dht.humidity)
Produces:
Temp: 22.5
Hum: 50.0
Lost access to message queue

The sensor values are correct and stable.
The message appears every time the GPIO line is accessed.
A way to suppress this message or fix the condition it is complaining about would be appreciated.

[brgl]

Hi! The message doesn't exist in libgpiod's source code nor does the library print anything to stderr ever. This must be coming from the higher lever program using libgpiod. You can run strace on the script and post the output here so, I should be able to tell you what's going on with GPIOs from the libgpiod's PoV at least.

[vfazio]

adafruit/libgpiod_pulsein@0af2ee6

adafruit/Adafruit_CircuitPython_DHT#50