fix

docker/entrypoint.sh

@@ -40,7 +40,7 @@ sed -i -E \
 
 # Keep the client-facing realm record in sync after restores and migrations.
 # Values are validated above before being interpolated into SQL.
-mariadb --protocol=tcp \
+mariadb --default-character-set=utf8mb4 --protocol=tcp \
     -h "${db_host}" -P "${db_port}" -u "${db_user}" "-p${db_password}" auth <<SQL
 INSERT INTO realmlist
     (id, name, address, localAddress, localSubnetMask, port, icon, flag,