Downgrade to older salt-minion version

steps.txt

#1. Remove the current version and clear app cache
sudo apt-get remove salt-minion
sudo apt-get clean
apt-get autoremove

#2. Create script to view all PPAs:
#Save as script as listppa.sh:
#! /bin/sh
# Script to get all the PPA installed on a system
for APT in `find /etc/apt/ -name \*.list`; do
    grep -Po "(?<=^deb\s).*?(?=#|$)" $APT | while read ENTRY ; do
        HOST=`echo $ENTRY | cut -d/ -f3`
        USER=`echo $ENTRY | cut -d/ -f4`
        PPA=`echo $ENTRY | cut -d/ -f5`
        #echo sudo apt-add-repository ppa:$USER/$PPA
        if [ "ppa.launchpad.net" = "$HOST" ]; then
            echo sudo apt-add-repository ppa:$USER/$PPA
        else
            echo sudo apt-add-repository \'${ENTRY}\'
        fi
    done
done

#3. View current list of PPAs
sh listppa.sh

#4. Remove old salt PPA from list:
vi /etc/apt/sources.list.d/saltstack.list

#5. Confirm its gone from list
sh listppa.sh

#6. Specify an older version -- visit here for available versions: https://repo.saltstack.com/
sudo wget -O - https://repo.saltstack.com/apt/ubuntu/16.04/amd64/archive/2016.3.7/SALTSTACK-GPG-KEY.pub | sudo apt-key add -
echo "deb http://repo.saltstack.com/apt/ubuntu/16.04/amd64/archive/2016.3.7 xenial main" > /etc/apt/sources.list.d/saltstack.list

#7. Try installing again
sudo apt-get install salt-minion

#8. Confirm new version
salt-minion --version

For anyone following this in the future, step 6.5 is to run sudo apt-get update to read in the new PPA.