Bad news (for me at least), during the night it got stuck and i got the errors from the first picture. I pressed enter and a while later it got stuck again (second picture). When i couldn't get it to move along i gave up and shut down the server, I'm posting the images here in case someone can make any use out of it...
BTW. Is there a bug report or similar on this? Because i think that this should be fixed somehow or at least ask for a confirmation from the user before accepting the change since it can do a lot of unintended damage.
It feels safer to stop now before everything breaks, so i started to reinstall freenas from scratch on a new usb stick and several hours later and i'm almost back on track. Apparently i learned something last round so it was much faster this time. Only transmission that refuses to play ball, but that's not for this thread...