Press F4 in Emulation Station to go to the command console. Then enter:

sudo apt clean # clears the update cache sudo apt autoremove # removes installed packages that are no longer needed by other packages (so-called dependencies) exit # exits the console back to Emulation Station

@mitu
Thanks. I guess I just want the error suppresed and any other errors as trawling through a gamelist.xml for mame is going to take some time.

Thanks for the tip.
Could you explain what do you mean exactly by : "using the RGUI I assigned the enable Turbo function to the same button I want to apply the Turbo function"?
I cannot find how to do this in RetroArch.

So far I created the cfg file for the game :
input_player1_turbo_btn = 1
input_player2_turbo_btn = 1

And I put this code retroarch.cfg :
input_turbo_period = 6
input_turbo_duty_cycle = 3