Solve Webmin/Debian Error: Failed to install module .deb : Not a valid module file : tar: This does not look like a tar archive

You are maybe, like me a few minutes ago, confused after following crappy instructions on the Webmin website about installing Virtualmin as a Webmin module; or you might have tried installing some other package with a .deb extension & run to an error looking like this:

Failed to install module webmin-virtual-server_3.93.gpl_all.deb : Not a valid module file : tar: This does not look like a tar archive tar: Skipping to next header tar: Exiting with failure status due to previous errors

The strangest thing is that when I googled the error I found several posts from people who had this same issue, but no one gave a solution that fixes this inside Webmin: Since the Virtualmin package came from the Webmin guys themselves along with the installation instructions, there sure is a fix.. But all I could find, after using a lot of imagination trying different keywords on Google, are the Shell commands allowing you to install DEB packages directly from your SSH client.. Well it’s probably a better method anyways.

So as an example let’s install the Virualmin package for Debian:

log-in to SSH & download the package to your server using this command:

wget http://download.webmin.com/download/webmin-virtual-server_3.93.gpl_all.deb

Note that you should replace the example URL above with the latest package link.

Now that you saved the package in your server you should run this command to install it:

dpkg -i webmin-virtual-server_3.93.gpl_all.deb

Note again that you should replace webmin-virtual-server_3.93.gpl_all.deb with the package you downloaded.