Comment 1 for bug 1885092

When looking at your output I have a feeling Diodon is already running.

Because when running Diodon a second time when it is already running it is trying to open a popup and this because of a race condition doesn't always work as of bug #1630375

But once Diodon is running you should see a paper clip in the top right corner which you can use to access the history. Or is this by any chance not there on Ubuntu 20.04? Are you using another shell than Gnome Shell?

What you can do to be sure is to run `killall diodon` and then start Diodon through the Shell again.