There is a workaround for symbolic links in shared folders to work again on VirtualBox 4.1.8+. Basically you need to run this command:
VBoxManage setextradata VM_NAME VBoxInternal2/SharedFoldersEnableSymlinksCreate/SHARE_NAME 1
You can do this in the Vagrant context by adding this to the Vagrant::Config.run your Vagrantfile:
config.vm.customize ["setextradata", :id, "VBoxInternal2/SharedFoldersEnableSymlinksCreate/SHARE_NAME", "1"]
More information can be found on Error VirtualBox # 10085 .
Note that the commenter who shares the setextradata trick forgets to tell you that the key name requires SHARE_NAME . I found this digging C code !
source share