The error logged with too old libjs-bootstrap4 is this: AH00037: Symbolic link not allowed or link target not accessible: /var/lib/roundcube/skins/elastic/deps/bootstrap.bundle.min.js, referer: https://example.com/webmail/?_task=mail&_action=compose
-- Frederik Himpe <fhi...@ai.vub.ac.be> Vrije Universiteit Brussel