ModuleNotFoundError only if script is launched by cron

[bowlofred]

Possibly your login environment has a PATH that points to one version of python and CRON is using the default system path that points to a different installation of python.

lancement.sh runs the python specified in the environment (the path) and that might be different between root and the "pi" account.

Try doing sudo su - and then try to run the script. Does it fail?