I upgraded from 1.3.9 to 1.4.11 and when I log into roundcube, every folder I've got is empty, including the inbox. IMAP server, running on the same machine, is dovecot. That's installed from Ubuntu 18 packages and works -- if I connect to it with thunderbird, everything's great.
On downgrade to 1.3.9, everything is OK. Initially I was getting an error with the downgrade but I figured out that I needed to restart php7.2-fpm to get 1.4.11 files out of its cache.
Any ideas or further troubleshooting steps?