I have the same problem, neither Gutenberg nor classic editor works. Downgrading seems to be the only solution.
I have the same problem, and Gutenberg only displays a blank, white page. Even with all plugins disabled. In one of my sites Gutenberg works (that’s the one where I tested the plugin earlier), but in the two where I never tested the plugin, Gutenberg does NOT work. The other difference is that where it works, WordPress resides in a subdirectory, where it does not work, in the root.
Update, it is the div below that grows too high, the offending line seems to be:
<div class=”main-sidebar col-md-3 col-sm-4 col-md-offset-1″>
