Thanks for your messages.

I have already install twisted but without "sudo".
I reinstall it with "sudo pip3 install twisted" and now the service run automaticly at startup.

Thanks for your help.

Hello, I have the same probleme than micksel. If I start it manually everything works fine: /home/pi/domoticz/plugins/IKEA-Tradfri$ python3 tradfri.tac But if I try with ikea-tradfri.service pi@raspberrypi:~ $ sudo service ikea-tradfri status ● ikea-tradfri.service - IKEA Tradfri COAP-adapter Loaded: ...