You need to be the user that is running HA. This depends on which version of AIO you used. Later ones the user was homeassistant, previously it was hass. Do ls /users to find out.
You need run the script to set up the virtual environment for hass, just as you do when you upgrade.
Here was my output
(homeassistant) homeassistant@raspberrypi:/home/pi $ hass --script influxdb_migrator -d home_assistant
Cloning from home_assistant to home_assistant__old
[####################################################################] 100.0%
Migrating from home_assistant__old to home_assistant
[####################################################################] 100.0%
(homeassistant) homeassistant@raspberrypi:/home/pi $ exit
exit
pi@raspberrypi:~
It took about 2.5 hours on my PI B+, so be patient.