virtualbox.org

I cannot share file through shared folder anymore (neither from host or guest)
The shared folder always worked till the last boot: any tip?

Host: Windows 10 Pro (with VirtualBox 6.1.22)
Guest: Kubuntu 20.04 LTS

Please provide a VM log file. Make sure the VM is fully shut down, then right click it in the manager UI. Select "Show Log" and save "VBox.log" (no other file) to a zip file. Attach the zip here.

Here there are the logs attached
Currently I removed shared folder, since it doesn't work

I don't see anything in the log that would be relevant to the issue your having (tho' someone else might). The host does have other limitations (dual-core CPU) which may impact on Host/VM performance; and the version of VirtualBox being used is getting 'rather old', but if it works for you then fine.

One thing to check is that, in my experience, if all Host shared folders are deleted from the settings for a Linux Guest then the Linux Distro will also automatically remove the user from membership of the vboxsf user group, so user membership of that group has to be reinstated if a shared folder is then added/recreated.

multiOS wrote:One thing to check is that, in my experience, if all Host shared folders are deleted from the settings for a Linux Guest then the Linux Distro will also automatically remove the user from membership of the vboxsf user group, so user membership of that group has to be reinstated if a shared folder is then added/recreated.

So have I to launch groupadd command for the user at the guest machine (once I have re-attached the shared folder)?
I don't remember I had done so the forst time, I will try

Edit: nope, user is already in vboxsf group, also I have added chmod 777 to mountpoint

I suggest you update to VirtualBox 6.1.36, including the 6.1.36 Guest Additions.

@korda,

The vboxsf user group is created automatically in a Linux VM when any shared folders are added to that VM via VirtualBox 'Settings' or the Devices > Shared Folders menu item in a running VM. What you need to do is add the user to that user group when the VM is running.

The method of adding users to groups can vary between the various linux distributions, but entering the following command in Terminal should work on an Ubuntu-based system, providing the user has admin privileges;
Resboot the VM after the command is accepted and check if the shared folders are visible to the user. Logging out and back in to the user account, instead of a reboot, also often works.

mpack wrote:I suggest you update to VirtualBox 6.1.36, including the 6.1.36 Guest Additions.

Done: it works again!!!
But I am wondering what happened since I have not update anything (nor guest nor host) between a correct boot and the subsequent failed.