If I plug/unplug my mobile phone while I have a Qt application running, that application spams the terminal with messages like this: UdevQt: unhandled device action "bind" UdevQt: unhandled device action "bind" UdevQt: unhandled device action "unbind" UdevQt: unhandled device action "unbind" The program works fine despite these error messages. These udev actions were added in Linux 4.12, see https://lkml.org/lkml/2017/7/18/962 .
I don't typically plug my phone into my computer, but today I did and saw similar messages, in blocks like this on my first root terminal: QObject::connect: invalid null parameter UdevQt: unhandled device action "bind" UdevQt: unhandled device action "bind" UdevQt: unhandled device action "unbind" UdevQt: unhandled device action "unbind" In dmesg was this: [21020.591193] usb 3-2: new high-speed USB device number 17 using xhci_hcd [21021.157302] FAT-fs (sdc1): FAT read failed (blocknr 1) [21021.157370] FAT-fs (sdc1): FAT read failed (blocknr 1) [21021.553779] usb 3-2: USB disconnect, device number 17 [21021.803208] usb 3-2: new high-speed USB device number 18 using xhci_hcd [21026.157203] FAT-fs (sdc1): FAT read failed (blocknr 1) [21026.157269] FAT-fs (sdc1): FAT read failed (blocknr 1) [21028.177721] usb 3-2: USB disconnect, device number 18 etc, etc in both cases. Linux kernel 4.17.19-gentoo KDE Frameworks 5.50.0 Qt 5.11.1 udev 238 Cheers.
I have the same error message each time I plug in (and out) my digital camera. My system has kernel 4.19.25, and is Slackware based. Though Slackware normally uses KDE, I have XFCE installed and most programs are Gtk based. The digital camera doesn't start any application. I manually start a (Python, using gphoto2) picture download program.
This has been fixed some time ago https://phabricator.kde.org/R245:8036f148fb66fb5f872712b44bd11e6d0d034756