3 of 3 Merged the useful information from the pastebin (some of the links are to old issues, probably unrelated).

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=192.168.0.103/var/ftp/ftpd/images/PersistenceUSBs/rsync-meld/allusers'

[Errno 95] Operation not supported: '/run/user/0/gvfs/ftp:host=192.168.0.103/var/ftp/ftpd/images/PersistenceUSBs/rsync-meld/allusers'.

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 defines the problem and provides the solution.

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

Possibly-related bugs include GNOME #317875 and GNOME #768281.