Man I can't thank you enough, it's finally working! If you PM me your details, you have a few beers from me :)
For anyone interested, after registering at screenscraper.fr and going through all SS flags arguments, I think I finally got it right:
/opt/retropie/supplementary/scraper/scraper -scrape_all=true -download_images=true -download_marquees=true -download_videos=true -console_src="ss,gdb,ovgdb" -mame_src="adb,mamedb,gdb" -use_nointro_name=true -ss_user="user_name" -ss_password="password"No more errors:
88a40a24-8e53-4c14-906c-0a9f06e443cd-image.png
