I encountered such issue when trying to set up a directory share for the user session in virt-manager and managed to narrow down the problem by looking at libvirt log in
$HOME/.cache/libvirt/qemu/log/<vm-name>-fs0-virtiofsd.log The error there was like this: [2025-10-09T17:12:23Z ERROR virtiofsd::sandbox] sandbox: couldn't setup id mappings: write to uid map failed: failed to execute newuidmap: No such file or directory (os error 2) Which indicated that it couldn't run newuidmap and naturally, I discovered that I had no uidmap package that provides it. Installing uidmap fixes is. I think it should be added as a dependency package for virtiofsd. Regards, Shmerl.
