virtualbox.org

Yesterday I installed Virtualbox (5.2.4r119785) on my Windows 10 x64 host, then downloaded and installed the latest version of Guest Additions, then installed Linux Mint Mate 64bit as a guest. In the settings for Linux Mint I set up a shared folder to a data drive so that I could e.g. use Linux for image editing, writing projects. When I start (run) the guest Linux, the shared folder is nowhere to be found. I have done what I just described perhaps a dozen times before in the past few years, with success (shared folder visible), I have set up virtualbox on windows and Linux hosts, and had both windows and linux guests, so I feel pretty comfortable installing a host and guest. I am puzzled why I can not get a shared folder, pretty much mandatory for my needs otherwise the guest Linux is useless to me. I am running Malwarebytes premium, could it be a firewall issue with Windows 10, or is Malwarebytes perhaps preventing a shared folder? I did install the guest encrypted, and installed Linux with an encrypted home folder-- I thought that might have caused issues so I installed a second Linux guest but without encryption except for an encrypted home folder, but the issue remains (no shared folder visible in Linux).

Can anybody help me solve this problem?

Hopefully this statement is out of the real order "then downloaded and installed the latest version of Guest Additions, then installed Linux Mint Mate 64bit as a guest" as you would actually need the guest installed to be able to install the guest additions in the guest. There is also a condition that could be possible if the above statement is in fact true. You installed the guest additions in the host and are relying on the guest which might have a subset of the additions installed by default which will not work properly. So have you installed the official guest additions in the guest?

It would also help if you posted the guests log file ( as an attachment )

Things are getting more promising!
So in the Linux guest I chose to Insert Guest Additions from the Vbox menu, then I right clicked the guest additions CD icon on the Linux desktop and chose to open it in a terminal. I ran the autorun.sh script there:
$ sudo su
$ sh autorun.sh
and Linux went to work building and installing the guest additions. I rebooted Linux (guest) and now the shared folder (drive) shows up as an icon on the Linux desktop.

I can only explore that shared folder as root though, by
$ sudo caja

So I am puzzled how I get access to the shared folder as my ordinary user that I set up when I installed the Linux guest? I went to the administration menu : users of Linux and elevated myself to administrator status, but still I can not explore the files in the shared folder unless I open caja (file explorer GUI) as root using 'sudo caja'. Still, nice to see the shared folder finally, just need to figure out how to make it accessible to my ordinary user account on Linux.

If you are using the auto-mount shared folder you must add your user to the vboxsf group on the guest followed with a reboot. However I have seen this type of share to be limited. I much prefer a manual mount and add the mount command to the /etc/rc.local file. That way you can assign the proper permissions and it seems to be of greater importance when you have a Windows host.

It is working now In the guest Linux i opened a terminal and added myself (linuxuser) to the group vboxsf
$ sudo adduser linuxuser vboxsf
where of course linuxuser is the name of the Linux user; now I am able to open the shared folder as linuxuser, see files and folders, open a file and modify it and save/overwrite it.

This was very important to me because I really want Linux for privacy, but I also must user Windows for music composing and video editing. I have used dual boot Windows + Linux. Butusing a virtual guest Linux, which is adequate for browsing, email, text editing, is great so I am instantly go back and forth between Linux guest and Windows host.

Thank you all for helping get this working!!!

Marking as [Solved].