I recently installed fluka and flair on Ubuntu 20.04 ,
and started practicing basic example, i was trying to run the example in
Official flair site ,
but the simulation not running, also i get error message (permission denied) when i click on plot button.
it seems you are running a FLUKA and Flair version, which is not supported by this forum.
We can only provide help for version installed from: https://fluka.cern/