Upgrade for postgresql versions

postgresql_upgrade

1. pg_lsclusters

2. Stop all clusters, even the new one you want to use.

pg_ctlcluster <version> main stop

3. cd /tmp

4. sudo -H -u postgres /usr/lib/postgresql/12/bin/pg_upgrade \
   -b /usr/lib/postgresql/10/bin \
   -B /usr/lib/postgresql/12/bin \
   -d /var/lib/postgresql/10/main \
   -D /var/lib/postgresql/12/main \
   -o ' -c config_file=/etc/postgresql/10/main/postgresql.conf' \
   -O ' -c config_file=/etc/postgresql/12/main/postgresql.conf'

if working:

5. Change following values in /etc/postgresql/12/main/postgresql.conf

listen_addresses = '*'
port = 5432       

6. Change file: /etc/postgresql/12/main/pg_hba.conf

This one: 
local   all             all                                     peer
for:
local   all             all                                     md5

and add:
host    all             all             0.0.0.0/0               md5

7. sudo pg_ctlcluster 12 main start