When I upgraded to VirtualBox 5.2.8 I lost the connection to the path “folders/myfolders”, but was able to use another path as a work-around. Now I am unable to get that path to work and I am searching for answers to this problem. My next attempt is to revert to an older version of Oracle VirtualBox which I am downloading now.
At first 5.2.6 did not work. The fix: In the Oracle VM VirtualBox Manager 5.2.6 click on File > Preferences then choose Extensions in the navigation pane. I found the extension pack for 5.2.8 listed so I deleted it and 5.2.6 started working perfectly.