I downloaded virtualbox version 6.0.8(I think) plus the extension pack, used it for a while and then this message started to show up ...E:The repository 'http://download.virtualbox.org/virtualbox/debian tessa Release' does not have a Release file.
I had the same problem with Google Earth, but I managed to purge it. I found the solution by searching in this forum.
I purged Virtualbox as well and used autoremove, but this message still pops up.
I did all the newbie things since I'm a newbie, copy and paste terminal commands.
But I'm lost right now and dont know what to do.