This post is also available in: French

When you experiment troubles with shared folders

When you need to try every single VirtualBox release, you often upgrade you system. The upgrades fortunately allow you to keep your old virtual machine working on you brand new install. Until this morning, I never faced problems after a VirtualBox upgrade. I was not able to mount my shared folders anymore. This problem:

/sbin/mount.vboxsf: mounting failed with the error: Protocol error

can be fixed easily, just re-installing the guest additions…