I'm not sure. The question contains the wrong assumption that after pressing Ctrl+Alt+F12 one must reboot. This addresses that. Since the question is asking why that is so, an explanation of how it is not so might be sufficient to make something an answer.
seems on-topic to me - the interpretation of that error message is about the software that produces the message and thus on-topic
not OT "EOL" - the release was supported when the question was asked; it doesn't really qualify for any close reason as far as I can tell (unless it turns out to be a duplicate)
dupe, after which a merge should perhaps be considered
As I understand it, it's asking how to install VirtualBox on an external drive and how to create virtual machines on that same external drive that will be used to run Ubuntu. Unless the host system also happens to be Ubuntu (in which case it is about running VirtualBox in Ubuntu, and is thus about Ubuntu), I don't think that's really about Ubuntu.
Installing VirtualBox on an external drive and making it put virtual machines on the external drive doesn't involve doing anything with Ubuntu, even if it will be used to run Ubuntu once it is successfully set up that way.
I guess it could be considered on-topic with the answer, "This is unaffected by what guest OS you run after you set it up."
I just don't see how this is more related to Ubuntu than if someone asked for a Windows download link for installing VirtualBox and mentioned that they wanted to run Ubuntu using it.
On the other hand, you have a point too, in that the OP may not know that this doesn't involve doing anything specific with Ubuntu.
Like, returning to the analogy, if someone asked for a Windows download link for "the version of VirtualBox for Ubuntu virtual machines," that would arguably be on-topic and should be answered by explaining that no specific version of VirtualBox is required.
Yes, but I am wondering also if we should report it as spam.
@karel It looks like you first noticed the problem and provided the feedback that generated that message, which I noticed. Thanks, and I apologize for not searching the web for strings from the post before giving my own wrong feedback.
@Zanna It might not be intended as spam. I'll flag NAA and vote to delete.
@EliahKagan The accepted answer to that question is correct and Draw.io is free software, but the accepted answer doesn't go far enough because it doesn't mention that the Draw.io snap package can be installed via Ubuntu Software. Draw.io is faster than Dia because it's easier to use and it makes higher resolution charts and diagrams. For wireframing you need a draw application that works fast.
