==== Odoo OpenUpgrade =====
You need a working installation of odoo 12, or almost postgresql database.
<code>
su - odoo
git clone --branch 13.0 --depth 1 https://github.com/OCA/OpenUpgrade.git
pip3 install git+git://github.com/OCA/openupgradelib.git
cd OpenUpgrade
./odoo-bin --update all --stop-after-init -d openupgrade
</code>

Before upgrade you will need create a working installation of odoo 13.

==== Odoo FE ====
After update do:
<code>
sudo -u odoo /opt/odoo/odoo-bin --stop-after-init -c /etc/odoo.conf -d openupgrade -u res_currency_cr_adapter --logfile=/tmp/odoo_openupgrade
sudo -u odoo /opt/odoo/odoo-bin --stop-after-init -c /etc/odoo.conf -d openupgrade -u l10n_cr_country_codes --logfile=/tmp/odoo_openupgrade
sudo -u odoo /opt/odoo/odoo-bin --stop-after-init -c /etc/odoo.conf -d openupgrade -u cr_electronic_invoice --logfile=/tmp/odoo_openupgrade
</code>

==== References ====
  * https://doc.therp.nl/openupgrade/migration_details.html