The Package Installer (GDebi) has failed on both packages I've tried installing with it in 20.10: Opera & OnlyOffice.
I had to resort to using sudo dpkg -i in the Terminal in order to install both of these packages.
If you think Gdebi is broken or has a bug please report it on Launchpad. Provide as much info as possible.:
Bug report is filed:
I just realized that this post that I originally put in "Thoughts & Feedback" were moved by a mod/editor (I don't know what they are called around here) to "Support & Help Requests". Just out of curiosity, what support or help was this post about? I solved my own problem. I installed these packages at the terminal using dpkg. I literally did not need support or help. I was actually trying to provide feedback about something that does not work as expected and would stymie a more casual user. It actually kind of ■■■■■■ me of a little that my feedback was moved to the support and help requests section.
I moved this post to Thougts & Feedback as requested.
By the way, you should install your *.deb files using apt with sudo apt install -y ./your.deb in its folder. It automatically solves dependencies issues that can appear when installing such packages.