See the `3.X <https://doc.powerdns.com/3/authoritative/upgrading/>`__
upgrade notes if your version is older than 3.4.2.
+4.1.0 to 4.1.1
+--------------
+
+- The :doc:`Generic MySQL backend <backends/generic-mysql>` schema has
+ changed: the ``notified_serial`` column default in the ``domains``
+ table has been changed from ``INT DEFAULT NULL`` to ``INT UNSIGNED
+ DEFAULT NULL``:
+
+ - ``ALTER TABLE domains MODIFY notified_serial INT UNSIGNED DEFAULT NULL;``
+
4.0.X to 4.1.0
--------------