Recommendation: keep disabled for better performance.
Enable for testing PowerDNS upgrades, without changing stored records.
+Enable for upgrading record content on secondaries, or when using the API (see :doc:`upgrade notes <../upgrading>`).
+Disable after record contents have been upgraded.
This option is supported by the bind and Generic SQL backends.
Before upgrading, please check your database for any non-ASCII content.
The interpretation of the non-ASCII bytes in those fields might change because of a different charset suddenly being used.
-Record type changes on secondaries
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+Record type changes
+^^^^^^^^^^^^^^^^^^^
The in-database format of the ``IPSECKEY``, ``SVCB``, ``HTTPS`` and ``APL`` records has changed from 'generic' format to its specialized format.
-It is recommended to re-transfer, using ``pdns_control retrieve ZONE``, all zones that have records of those types, or ``TYPExx``, for numbers 42, 45, 64, 65.
+
+On secondaries, it is recommended to re-transfer, using ``pdns_control retrieve ZONE``, all zones that have records of those types, or ``TYPExx``, for numbers 42, 45, 64, 65.
+Then, disable the setting again.
+
+API users might notice that replacing records of these types leaves the old TYPExx records around, even if PowerDNS is not serving them.
+To fix this, enable :ref:`setting-upgrade-unknown-types` and replace the records; this will then delete those TYPExx records.
+Then, disable the setting again, because it has a serious performance impact on API operations.
PostgreSQL configuration escaping
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^