id summary reporter owner description type status component version resolution keywords cc guest host 16697 Guest Additions shared folders broken with 5.1.20 on RHEL 7 cknz "Blogged at http://distracted-it.blogspot.co.nz/2017/04/virtualbox-5120-bug-with-shared-folders.html After installing GA for 5.1.20, shared folders no longer mount: {{{ # mount host_home mount: wrong fs type, bad option, bad superblock on host_home, missing codepage or helper program, or other error In some cases useful info is found in syslog - try dmesg | tail or so. # dmesg | tail ... [ 334.616717] vboxsf: Successfully loaded version 5.1.20 (interface 0x00010004) [ 343.413650] sf_read_super_aux err=-22 }}} Looking around the problem is caused by a broken symlink to mount.vboxsf {{{ # updatedb # locate mount.vbox /opt/VBoxGuestAdditions-5.1.20/lib/VBoxGuestAdditions/mount.vboxsf /usr/sbin/mount.vboxsf # ls -l /usr/sbin/mount.vboxsf lrwxrwxrwx. 1 root root 49 Apr 26 10:04 /usr/sbin/mount.vboxsf -> /opt/VBoxGuestAdditions-5.1.20/other/mount.vboxsf }}} Aha, it seems that mount.vboxsf is a broken link; the following are not the same: {{{ /opt/VBoxGuestAdditions-5.1.20/lib/VBoxGuestAdditions/mount.vboxsf <--- available /opt/VBoxGuestAdditions-5.1.20/other/mount.vboxsf <--- pointed at }}} Bit of a quicky fix: {{{ # rm -f /usr/sbin/mount.vboxsf # ln -s /opt/VBoxGuestAdditions-5.1.20/lib/VBoxGuestAdditions/mount.vboxsf \ /usr/sbin/mount.vboxsf # ls -l /usr/sbin/mount.vboxsf lrwxrwxrwx. 1 root root 66 Apr 26 10:16 /usr/sbin/mount.vboxsf -> /opt/VBoxGuestAdditions-5.1.20/lib/VBoxGuestAdditions/mount.vboxsf Moment of truth: # mount host_home $ mount ... host_home on /home/ckerr/host_home type vboxsf (rw,nodev,relatime) }}}" defect closed guest additions VirtualBox 5.1.20 duplicate vboxsf sf_read_super_aux mount symlink broken Linux Windows