When uploading a site logo, I get a 403 Forbidden HTTP error.
Also, the Inspect Element preview shows this page:
On the site itself, it just says "http error". I tried disabling nonces, no change. I had done
chmod -R 750 <web root dir> and
chown -R www-data:www-data <web root dir> too, so I assume permissions are not the issue. (Yes, php-fpm and my web server are running as www-data.)
This is a default install from Wordpress stable version. I have removed my plugins folder too, no change. My web server is NGINX.