Software Boutique is broken on 18.04

This bug has been reported on the Ubuntu ISO testing tracker.

A list of all reports related to this bug can be found here:
http://iso.qa.ubuntu.com/qatracker/reports/bugs/1741607

AIUI this is to be expected for now, because the developers are working on the new version.

@Konrad Does this Software Boutique problem still exists in Ubuntu-Mate 18.04.1 final release? If not - please close this bugreport

@Mantas I just checked that and luckily, this problem does not exist in Ubuntu Mate 18.04.1, so I'm marking this bug as "Fix Released".

In Ubuntu MATE 20.04.3, PlayOnLinux won't install because it requires Python 2 which has been depreciated. VirtualBox won't install because it requires the installation media to be a CD.

Who is responsible for checking the packages in the Software Boutique and keeping them up to date?

Please check your repositories.

I can't reproduce your issue on fresh Ubuntu MATE 20.04.3 LTS VM without any third-party repositories. I have successfully installed both PlayOnLinux and VirtualBox from Software Boutique.

```
$ cat /etc/os-release
NAME="Ubuntu"
VERSION="20.04.3 LTS (Focal Fossa)"
ID=ubuntu
ID_LIKE=debian
PRETTY_NAME="Ubuntu 20.04.3 LTS"
VERSION_ID="20.04"
HOME_URL="https://www.ubuntu.com/"
SUPPORT_URL="https://help.ubuntu.com/"
BUG_REPORT_URL="https://bugs.launchpad.net/ubuntu/"
PRIVACY_POLICY_URL="https://www.ubuntu.com/legal/terms-and-policies/privacy-policy"
VERSION_CODENAME=focal
UBUNTU_CODENAME=focal

$ sudo snap refresh
All snaps up to date.
$ snap list
Name Version Rev Tracking Publisher Notes
core18 20210722 2128 latest/stable canonical✓ base
snapd 2.51.4 12883 latest/stable canonical✓ snapd
software-boutique 0+git.f633ffb 54 latest/stable/… flexiondotorg classic
ubuntu-mate-welcome 21.04.0-ef35c052 626 latest/stable/… flexiondotorg classic

$ grep -r ^deb /etc/apt/ --include=*.list
/etc/apt/sources.list:deb http://archive.ubuntu.com/ubuntu/ focal main restricted
/etc/apt/sources.list:deb http://archive.ubuntu.com/ubuntu/ focal-updates main restricted
/etc/apt/sources.list:deb http://archive.ubuntu.com/ubuntu/ focal universe
/etc/apt/sources.list:deb http://archive.ubuntu.com/ubuntu/ focal-updates universe
/etc/apt/sources.list:deb http://archive.ubuntu.com/ubuntu/ focal multiverse
/etc/apt/sources.list:deb http://archive.ubuntu.com/ubuntu/ focal-updates multiverse
/etc/apt/sources.list:deb http://archive.ubuntu.com/ubuntu/ focal-backports main restricted universe multiverse
/etc/apt/sources.list:deb http://security.ubuntu.com/ubuntu focal-security main restricted
/etc/apt/sources.list:deb http://security.ubuntu.com/ubuntu focal-security universe
/etc/apt/sources.list:deb http://security.ubuntu.com/ubuntu focal-security multiverse

$ sudo apt update -qq && apt list --upgradable
All packages are up to date.
Listing... Done

$ dpkg -l | grep -vE "^ii|\|^Desired|"
$
```

Please prepare full info about your system and post topic about your problem on http://ubuntu-mate.community/ to get help.
Current bug is fixed. Your last comment is not about a bug, so LP is a wrong place for rants like "Who is responsible...".
Testers are always welcome, you can play your role nicely anytime.