I was running a MariaDB server installed via APT repositories (from mariadb.org) with the following packages :

• mariadb-server-10.2 (10.2.10+maria~stretch)
• mariadb-plugin-tokudb (10.2.10+maria~stretch)

After running an apt-get upgrade, mariadb-server was upgraded to 10.2.11+maria~stretch but mariadb-plugin-tokudb was not...

Now, TokuDB tables are unusable.
TokuDB Storage Engine can not be loaded anymore:

MariaDB [(none)]> INSTALL SONAME 'ha_tokudb';

ERROR 1126 (HY000): Can't open shared library 'ha_tokudb.so' (errno: 8, API version for STORAGE ENGINE plugin TokuDB not supported by this version of the server)