Can't install Debian packages for programs not in the Ubuntu repositories

[Ads20000]

Impact
------
It is not possible to use the default Software app to install .debs for packages that are not already available in Ubuntu.

Test Case
---------
1.
a. Download a .deb that is not already in Ubuntu.
It is important that the package not be available in your local apt cache.
https://www.google.com/chrome/
https://itch.io/app
https://www.opera.com/download/get/?partner=www&opsys=Linux&product=Opera%20beta&package=deb

b. Open the .deb with gnome-software
gnome-software --local-filename=itch_23.4.1_amd64.deb

gnome-software should open to a page with an Install button for the package.

Click Install and verify that the app is installed.

What Happens
------------
The test fails. On Ubuntu 17.04, I get a popup
"Sorry, this did not work
The file is not supported."

Regression Potential
--------------------

Original Bug Report
-------------------
I still get the bug from the second test case in bug 1672424 on Ubuntu 17.04.

ProblemType: Bug
DistroRelease: Ubuntu 17.04
Package: gnome-software 3.22.7-0ubuntu3
ProcVersionSignature: Ubuntu 4.10.0-22.24-generic 4.10.15
Uname: Linux 4.10.0-22-generic x86_64
NonfreeKernelModules: zfs zunicode zavl zcommon znvpair
ApportVersion: 2.20.4-0ubuntu4.1
Architecture: amd64
CurrentDesktop: Unity:Unity7
Date: Thu May 25 10:27:49 2017
InstallationDate: Installed on 2016-11-01 (204 days ago)
InstallationMedia: Ubuntu 16.10 "Yakkety Yak" - Release amd64 (20161012.2)
SourcePackage: gnome-software
UpgradeStatus: Upgraded to zesty on 2017-04-17 (37 days ago)

[Ads20000 (ads20000)]

I copied the layout from bug 1672424 but edited it accordingly. Also, it doesn't happen now, but at first when trying to install an app by launching gnome-software by loading the Deb graphically (e.g. clicking on it in Firefox's download list), I was able to click the Install button in Ubuntu Software (gnome-software; the 'Sorry, this does not work' popup didn't load in this case), but aside from pressing inwards like you'd expect a button to appear when you click on it, there was no graphical response and the app didn't install. Now I just get the popup appear when launching Ubuntu Software graphically from a Deb too.

[Ads20000 (ads20000)]

Sam Korson who also got this bug said ( https://bugs.launchpad.net/ubuntu/+source/gnome-software/+bug/1672424/comments/56 ):

'my issue seems to have been resolved now either way; I just noticed that there were some "system updates" available from inside Software and I installed those and rebooted. I can now install .deb files without problems. Great!'

But most users don't go to that part of Ubuntu Software regularly? Why do these need to be installed? I don't understand why there's two different graphical update mangers in the first place...

[Ads20000 (ads20000)]

I haven't installed the update there to see if that resolves this issue because I'm not sure people should be running into this in the first place?

[Jeremy Bícha (jbicha)]

> I haven't installed the update there to see if that resolves this issue because I'm not sure people should be running into this in the first place?

While we try to fix all bugs before release, that is not always possible and this bug was mentioned in the Ubuntu 17.04 Release Notes [1]. If you do not install the update to fix this bug and restart your computer, then you will still be affected by this bug.

Therefore, I am closing this bug since it's already been fixed. If it still does not work after installing all updates and restarting your computer, please file a new bug with details of what is not working.

Thank you for taking the time to report this issue and help make Ubuntu better.

[1] https://wiki.ubuntu.com/ZestyZapus/ReleaseNotes#Desktop