Hey you all,
I know it is an old thread, but, same problem here.
I am runnung OMV 4.1.21 | 32 bit | 4.14.98 proxmox kernel | omvextrasorg 4.1.15
The VirtualBox plugins doesn't appear for me, no matter what.
I have already uninstalled and installed omv-extras (stable and testing repo) and done most everything I found in the forum, but still nothing.
The thing I could not do was enable and disable backports, I either get a "time out" or a "communicate failure" answer.
I'd really appreciate any help.
This is the apt-clean response: