Dear All,
First time I have an issue with upgrading Home Assistant (been upgrading to every update since last year).
The solution I found to get past the permissions issue by following the steps here: Cannot upgrade, corrected for the right order as described in the last post.
Therefore:
$ sudo systemctl stop [email protected]
$ sudo chown homeassistant:homeassistant -R /srv/homeassistant/
$ sudo su -s /bin/bash homeassistant
$ source /srv/homeassistant/bin/activate
$ pip3 install --upgrade homeassistant
$ exit
$ sudo reboot
hass --script check_config
Worked out for me.
Hope this can be useful to others.
Best