+5593. [bug] Journal files written by older versions of named
+ can now be read when loading zones so that journal
+ incompatibility will not cause problems on upgrade.
+ Outdated journals will be updated to the new format
+ after loading. [GL #2505]
+
5592. [bug] Add globally available thread_id (isc_tid_v) that's
incremented for each new thread, but the old thread
ids are reused, so the maximum thread_id always
(crash) if the return of stale cached answers was enabled and
``stale-answer-client-timeout`` was applied to a client query in process.
This has been fixed. [GL #2503]
+
+- Zone journal (``.jnl``) files created by versions of ``named`` prior
+ to 9.16.12 were no longer compatible; this could cause problems when
+ upgrading if journal files were not synchronized first. This has been
+ corrected: older journal files can now be read when starting up. When
+ an old-style journal file is detected, it is updated to the new
+ format immediately after loading.
+
+ Note that journals created by the current version of ``named`` are not
+ usable by versions prior to 9.16.12. Before downgrading to a prior
+ release, users are advised to ensure that all dynamic zones have been
+ synchronized using ``rndc sync -clean``.
+
+ A journal file's format can be changed manually by running
+ ``named-journalprint -d`` (downgrade) or ``named-journalprint -u``
+ (upgrade). Note that this *must not* be done while ``named`` is
+ running. [GL #2505]