I am seeing the same issue on Debian 11 with the flatpak qFlipper.
The serial port is definitely available to my user and I can access the CLI as well. However, qFlipper (started from the same terminal window that can access the CLI) can not access the serial port:
185 [APP] qFlipper version 1.3.0 commit 01fcfec9 2023-03-27T11:51:38
185 [APP] OS info: KDE Flatpak runtime 5.15-21.08 5.10.0-22-amd64 Qt 6.4.3
202 [REG] Detected new device: VID_0x483:PID_0x5740
534 [UPD] Fetched update information from https://update.flipperzero.one/firmware/directory.json
553 [DBG] Trying serial port at /dev/ttyACM0
553 [DBG] Trying serial port at /dev/ttyUSB0
553 [DBG] Trying serial port at /dev/ttyS0
3696 [DBG] Trying serial port at /dev/ttyACM0
3696 [DBG] Trying serial port at /dev/ttyUSB0
3696 [DBG] Trying serial port at /dev/ttyS0
3720 [REG] Device initialization failed: Failed to find a suitable serial port
5589 [default] QStandardPaths: wrong permissions on runtime directory /run/user/1000, 0755 instead of 0700
23421 [APP] qFlipper exited
Last time I know it was working was on April 21:
239 [APP] qFlipper version 1.3.0 commit 01fcfec9 2023-03-27T11:51:38
239 [APP] OS info: KDE Flatpak runtime 5.15-21.08 5.10.0-21-amd64 Qt 6.4.3
256 [REG] Detected new device: VID_0x483:PID_0x5740
584 [DBG] Trying serial port flip_REDACTED at /dev/ttyACM0
584 [DBG] Using serial port flip_REDACTED at /dev/ttyACM0
585 [RPC] Starting RPC session...
684 [RPC] RPC session started successfully.
Note how the serial port when working is “Trying serial port flip_REDACTED at /dev/ttyACM0” and “Trying serial at /dev/ttyACM0”. REDACTED is the name of my FZ, so qFlipper got that information from somewhere before trying to open ttyACM0. In other word, an error that is not logged occurs before access to the serial port fails.
- other than updates, the computer did not change (e.g. no reconfiguration, no software install or uninstall)
- qFlipper did not change
- flatpak runtime did not change
- Flipper Zero firmware did change (from 0.80.1 to 0.81.1) [behavior is the same with 0.82.3]
I suspect that a change in the Flipper Zero firmware is the culprit.