Please add the info requested in https://retropie.org.uk/forum/topic/3/read-this-first to your post.

@mitu This makes even more sense especially, considering that SNES and PS1 where the problems for me. Hopefully this discovery can help further improve the next iteration of RetroPie.

@Robinson No, you copy the ROM files directly into the folder, and that's true for each system - you don't have to create separate folders for each ROM.

@ililil said in Post preparation actions for ROMs:

where can I find them?

Not here, see the forum rules.

@deodekabokat If you're on the command line, you can use mc (maybe you're familiar with the Norton Commander/Dos Navigator/etc. interface) and navigate around the filesystem.
Otherwise, you can copy the file on the ROMs folder and look at it over file shares

cp /etc/emulationstation/es_systems.cfg $HOME/RetroPie/roms

I'd advise to use the full image - and not the Berryboot variant - if you can spare a SD card for a few days while you tinker with RetroPie.

@mitu hey. thanks for your help. Did not know that Linux was case sensitive. Changed all folders, and did a find and replace to all lower case in the xml and all is good! Noob at all this but I am learning alot as I go. Thanks again for the help!