check, if you have a working /usr/bin/openssl
/usr/bin/openssl version file /usr/bin/openssl ldd /usr/bin/openssl
check, if you have a valid signature-file for freebsd-update
/var/db/freebsd-update/pub.ssl (you can safely remove it, because a new run of freebsd-update fetches it again)
After that the update should proceed without failures (e.g. from 11.0-RELEASE to 11.1-RELEASE)
freebsd-update -r 11.1-RELEASE upgrade freebsd-update install reboot your system freebsd-update install