'Permission error while locking the device' after Logging out and switching user

[MumuMundo]

Hello everyone and thanks awawa-dev for the great app and support!

So I made HyperHDR work with my Skydimo LED strip on Mint 22, but it has an issue since I added a second user to the system.

Whenever I log out as one user and log in as the other one I get this error 'Permission error while locking the device' and the LEDs won't turn on. It only works if I restart or if before logging out I do sudo pkill hyperhdr in the terminal.

If I only switch user (without logging out first) it will keep running as the other user and sometimes grabs screen colors from there.

2026-05-08T17:59:57.704Z [LEDDEVICE0_SKYDIMO] (LedDevice.cpp:403) Device is not ready to start a timer
2026-05-08T18:00:00.173Z [LEDDEVICE0_SKYDIMO] The LED device is not ready... trying to reconnect (try 26/60).
2026-05-08T18:00:00.173Z [LEDDEVICE0_SKYDIMO] Opening UART: ttyUSB0
2026-05-08T18:00:00.173Z [LEDDEVICE0_SKYDIMO] (ProviderSerial.cpp:209) _serialPort.open(QIODevice::ReadWrite): ttyUSB0, Baud rate [115200]bps
2026-05-08T18:00:00.202Z [LEDDEVICE0_SKYDIMO] (ProviderSerial.cpp:214) portName:          ttyUSB0
2026-05-08T18:00:00.202Z [LEDDEVICE0_SKYDIMO] (ProviderSerial.cpp:215) systemLocation:    /dev/ttyUSB0
2026-05-08T18:00:00.202Z [LEDDEVICE0_SKYDIMO] (ProviderSerial.cpp:216) description:       USB Serial
2026-05-08T18:00:00.202Z [LEDDEVICE0_SKYDIMO] (ProviderSerial.cpp:217) manufacturer:      1a86
2026-05-08T18:00:00.202Z [LEDDEVICE0_SKYDIMO] (ProviderSerial.cpp:218) productIdentifier: 0x7523
2026-05-08T18:00:00.202Z [LEDDEVICE0_SKYDIMO] (ProviderSerial.cpp:219) vendorIdentifier:  0x1a86
2026-05-08T18:00:00.202Z [LEDDEVICE0_SKYDIMO] (ProviderSerial.cpp:220) serialNumber:      
2026-05-08T18:00:00.202Z [LEDDEVICE0_SKYDIMO] Device 'skydimo' is disabled due to an error: 'Permission error while locking the device'

[awawa-dev]

Hi
HyperHDR can only run one instance at a time. While it usually checks for existing processes at startup, it cannot detect them across different users due to process isolation. Furthermore, assuming the second user belongs to dialout group, serial ports do not support shared access, so any application on the other session using that port would cause the same error .

[MumuMundo]

Thank you! Yeah I guess I shouldn't expect it to work when I switch user, but it happens even after I log out. Isn't there a way to for example to make the system run pkill hyperhdr automatically on logout? I asked AI about it but got dumb solutions that didn't work.

[awawa-dev]

Make sure you didn't run it as a service. If you run HyperHDR as an application from the menu it should be closed automatically by the OS on the user logout.