@ThierryOfNantes  The "install" option for nifi.sh was removed as of NiFi 2.x release because of the nuisances of the many different linux distributions that exist today. I am not implying that is your issue here, but wanted you to be aware that I could be a contributing factor to your issue. Since you can successfully start NiFi manually using the ./bin/nifi.sh start command, NiFi is working fine.  So the permission issue is outside of NiFi.  What user are you logged in as when you issue the command systemctl start nifi?  Is that user able to sudo to your run.as user? Perhaps try enabling debug on your journalctl log to see ifget more detail on where the permission denied is coming from. Hope this helps, Matt ... View more