this is an old thread but in gnome bug reports it is a recent open issue so it may be of some use to anyone searching for hours for a solution to fix gvfs-fuser issues - which all seem to be tightly related.

Error Msg from meld:

    Error copying '/media/root/5FDA03906F33F217/SAVE/rsyncTEST-usb/allusers' to '/run/user/0/gvfs/ftp:host='

    [Errno 95] Operation not supported: '/run/user/0/gvfs/ftp:host='.

I encountered the gvfs-fuser issue attempting to use meld/diff/kdiff over ftp.  Seems the problem is between fuser and gvfs.  The problem seems not to occur in 3.15.1 but begins being reported in 3.15.2.(the new python ver?)
Solution is a workaround not a fix - files/directories will copy but error is still displayed.

[Christopher's answer][1] defines the problem and provides the solution.

Another possible solution is using sshfs (see [this comment][2] and [this thread][3]). For more information on `gvfs-commands`, see [What is the difference between gvfs commands and common commands like cat, ls, cp?][4]

Possibly-related bugs include [GNOME #317875][5] and [GNOME #768281][6].