At last I have found the issue.
When I run $ sudo apt-get update
I see xenial-updates
in the list.
Hit:1 http://packages.microsoft.com/repos/edge stable InRelease
Hit:2 http://dl.google.com/linux/chrome/deb stable InRelease
Hit:3 http://ppa.launchpad.net/inkscape.dev/stable/ubuntu focal InRelease
Hit:4 http://us.archive.ubuntu.com/ubuntu focal InRelease
Hit:5 https://download.virtualbox.org/virtualbox/debian focal InRelease
Get:6 http://us.archive.ubuntu.com/ubuntu focal-updates InRelease [114 kB]
Hit:8 http://dk.archive.ubuntu.com/ubuntu xenial InRelease
Hit:9 http://dk.archive.ubuntu.com/ubuntu xenial-updates InRelease
Get:10 http://us.archive.ubuntu.com/ubuntu focal-backports InRelease [101 kB]
Get:11 http://us.archive.ubuntu.com/ubuntu focal-security InRelease [114 kB]
Hit:7 https://packagecloud.io/slacktechnologies/slack/debian jessie InRelease
Fetched 328 kB in 4s (89.5 kB/s)
Reading package lists... Done
But xenial is for ubuntu 16.04. So, I have to remove this.
I was looking for in /etc/apt/sources.list
file. But not found.
Then I found it in /etc/apt/sources.list.d/xenial.list
file and commented all lines [by adding #(hash) before each line], and saved file.
# deb http://dk.archive.ubuntu.com/ubuntu/ xenial main
# deb http://dk.archive.ubuntu.com/ubuntu/ xenial universe
#deb http://dk.archive.ubuntu.com/ubuntu/ xenial-updates universe
Now I run $ sudo apt --fix-broken install
. And it removed the old version of playonlinux wine wine1.6-i386:i386 winetricks
.
And now everything works.
So, when upgrade OS version, you must have to remove software source of older OS version.
I hope it helps someone. Thanks.