Downgrade Ubuntu

Trying to Downgrade Ubuntu from 22.04 to 20.04

Due to Mellanox Driver Compatability
Source

1. Backup the old sources.list file

cd /etc/apt/
mv sources.list sources.list-old

2. Add Ubuntu 20.04 LTS (Focal Fossa) repository

###Open
vim sources.list

###Add

deb http://tr.archive.ubuntu.com/ubuntu focal main restricted
#deb-src http://tr.archive.ubuntu.com/ubuntu focal main restricted
deb http://tr.archive.ubuntu.com/ubuntu focal-updates main restricted
#deb-src http://tr.archive.ubuntu.com/ubuntu focal-updates main restricted
deb http://tr.archive.ubuntu.com/ubuntu focal universe
#deb-src http://tr.archive.ubuntu.com/ubuntu focal universe
deb http://tr.archive.ubuntu.com/ubuntu focal-updates universe
#deb-src http://tr.archive.ubuntu.com/ubuntu focal-updates universe
deb http://tr.archive.ubuntu.com/ubuntu focal multiverse
#deb-src http://tr.archive.ubuntu.com/ubuntu focal multiverse
deb http://tr.archive.ubuntu.com/ubuntu focal-updates multiverse
#deb-src http://tr.archive.ubuntu.com/ubuntu focal-updates multiverse
deb http://tr.archive.ubuntu.com/ubuntu focal-backports main restricted universe multiverse
#deb-src http://tr.archive.ubuntu.com/ubuntu focal-backports main restricted universe multiverse
deb http://tr.archive.ubuntu.com/ubuntu focal-security main restricted
#deb-src http://tr.archive.ubuntu.com/ubuntu focal-security main restricted
deb http://tr.archive.ubuntu.com/ubuntu focal-security universe
#deb-src http://tr.archive.ubuntu.com/ubuntu focal-security universe
deb http://tr.archive.ubuntu.com/ubuntu focal-security multiverse
#deb-src http://tr.archive.ubuntu.com/ubuntu focal-security multiverse

3. Create preferences file

###Open
vim /etc/apt/preference.d/focal

###Add
Package: *
Pin: release n=focal
Pin-Priority: 1001

Package: *
Pin: release n=focal-updates
Pin-Priority: 1002

Package: *
Pin: release n=focal-security
Pin-Priority: 1003

4. Start Downgrade

apt update -y
apt install aptitude -y

#May need to repeat the following step several times
aptitude dist-upgrade -y
apt --fix-broken install

--> Failed.. Do Reinstall for Downgrade..!