Hi, after many useless attempts (I don't use Clover) thanks to all your suggests I could install High Sierra on my system. I used a Clover pen to install on a standard HD, rebooted to Clover pen and then updated directly from Applestore. Rebooted with the Clover pen directly to the brand new High Sierra hd. No problems at all. Now I boot via Enoch 2905 and everything works perfectly. Thanks all.