Don't waste your time reinstalling. I was able to track this down to a config file encoding issue. For me, it was /etc/salt/minion.d/_schedule.conf. I am not sure how the file was encoded the way it was, since the host and client systems are all linux variants, but it looks like it's using an encoding common on windows:
Bash
batkinson@hc2-omv:/etc/salt/minion.d$ file _schedule.conf
_schedule.conf: ISO-8859 text, with no line terminators
Opening the file, I found a garbled mix of what looked like appropriate content. I removed the file and was able to perform the upgrade and continue to use the configuration.