Have you tried on different computers / browsers?
Just got it working. Or seems to be. Been stable for a bit now and the admin page is back.
Had to replace the URL of the site, with localhost:localport
What browser are you on, and can you take a screenshot of the expanded error?
@PitaJ i'm on Safari on osx
I've the same problem on chrome and firefox too.
@PitaJ do you think is better if i open an issue on github ?
Yes please. Does this happen on other browsers?
@julian i've checked firefox, chrome and safari on osx
the problem is in my persona's child theme, i've to find what is changed
Change stylesheet.css to client css. See breaking changes thread.
@baris can you address me to the right thread ?