Just had a weird experience with the
dub snap package that I maintain: trying to use it in a 32-bit 14.04 VirtualBox install that I use for testing, I got the above error.
/snap/dub directory, I found that all the version directories (including
current) appeared to be empty.
apt update; apt upgrade and a restart, things were available once again.
I don’t have any idea what could have happened, but the error message asked that I report it, so consider it reported