Problems mounting partitions in a VM without passwordless sudo

Dunno if this is specific to Qubes or not, but without passwordless root installed, when I try to mount attached usb partition, ie with udisksctl mount -b /dev/xvdi command, it returns

Error mounting /dev/xvdi: GDBus.Error:org.freedesktop.UDisks2.Error.Failed: Error mounting system-managed device /dev/xvdi: Unknown error when mounting /mnt/removable

Internet search doesn’t seem to return any udisks2 errors with Unknown message, so I thought maybe this is qubes specific.

Error message reproduced on fedora-minimal and full fedora. I should mention that if you attach the whole usb device to the fedora-minimal based vm, then it can be attached in thunar without any problems. Problem is only with the attached partition.

So far I tried changing polkit permissions in /etc/polkit-1/rules.d/50-udiskie.rules as follows

polkit.addRule(function(action, subject) {
  var YES = polkit.Result.YES;
  var permission = {
    // required for udisks1:
    "org.freedesktop.udisks.filesystem-mount": YES,
    "org.freedesktop.udisks.luks-unlock": YES,
    "": YES,
    "": YES,
    // required for udisks2:
    "org.freedesktop.udisks2.filesystem-mount": YES,
    "org.freedesktop.udisks2.encrypted-unlock": YES,
    "org.freedesktop.udisks2.eject-media": YES,
    "org.freedesktop.udisks2.power-off-drive": YES
  if (subject.isInGroup("user")) {
    return permission[];

and in /etc/polkit-1/rules.d/allow-mount-internal.rules

polkit.addRule(function(action, subject) {
    if (( == "org.freedesktop.udisks2.filesystem-mount-system" || == "org.freedesktop.udisks.filesystem-mount-system-internal") &&
        subject.local && && subject.isInGroup("user"))
            return polkit.Result.YES;

As far as I can see this should work - user is a part of group user - or am I missing something?
Wouldn’t want to install passwordless root just to be able to mount a usb partition…

Does adding

/dev/disk/by-label/MY_LABEL /mnt/removable/MY_LABEL auto nosuid,nodev,user,nofail,x-gvfs-show 0 0

to the template’s fstab help to mount partition?