I was hoping this was something with my system, but I've now reproduced this in 3 different notebooks.
The main symptom is either a blank page when accessing the standard server interface (the with /tree at the end) or a page no stylized at all due to the lack of css.
Chrome shows net::ERR_SPDY_PROTOCOL_ERROR on main.js request
Edge shows weird errors (failure to open main.js)
This is sometimes accompanied by other errors or happens on different files. This also goes away and comes back intermittently .