GVFS (Gnome Virtual Filesystem)

GVFS or gio mount allows access to different types of network filesystems like SMB/CIFS and protocols like FTP or SFTP.

If Nautilus access to such a destination or a gio mount ... does not work, following can be used to see what happens inside gvfsd:

GVFS_SMB_DEBUG=10 GVFS_DEBUG=1 $(find /usr/lib* -name gvfsd 2>/dev/null) --replace

of if Kerberos is involved and might be the issue:

KRB5_TRACE=/dev/stdout GVFS_SMB_DEBUG=10 GVFS_DEBUG=1 $(find /usr/lib* -name gvfsd 2>/dev/null) --replace