Am 07.06.21 um 14:35 schrieb mpan via arch-general:
Thank you friends for your trying to help. But none of the suggestions worked. In fact I had already tried those before writing to the mailing list. Finally one of my friends (not in mailing list) suggested me to install 'shotwell' ( https://archlinux.org/packages/community/x86_64/shotwell/), and it solved the problem. After installing 'shotwell', when I made the camera 'on' after connecting to my PC's USB the camera got mounted and the icon came up on the Desktop. I reported it here as an information service. Thank you all. Shotwell is a pictures browser, unrelated to handling cameras by the file manager or desktop environment. It seems to be a coincidence caused by installation of one of the dependencies of the shotwell package. Therefore the issue is not solved.
Of all its dependencies the only ones I see, that do relate to photos access and wouldn’t be installed already on Arch Linux as the base dependencies, is libgphoto2 and whatever it needs. Which would be installed as a dependency of gvfs-gphoto2 suggested above.
It might simply be an incidental restart between the tests. libgphoto2 installs udev rules that might require a system restart or a reload of the udev rules. gvfs-gphoto2 installs a systemd user service and a gvfs monitor, which might require a restart of the user session.