Ref Guide: Upgrade Notes for 8.2 (neglected to do earlier)
diff --git a/solr/solr-ref-guide/src/solr-upgrade-notes.adoc b/solr/solr-ref-guide/src/solr-upgrade-notes.adoc
index 760fba7..6b4d4d5 100644
--- a/solr/solr-ref-guide/src/solr-upgrade-notes.adoc
+++ b/solr/solr-ref-guide/src/solr-upgrade-notes.adoc
@@ -31,6 +31,44 @@
If you are upgrading from 7.x, see the section <<Upgrading from 7.x Releases>> below.
+=== Solr 8.2
+
+See the https://cwiki.apache.org/confluence/display/SOLR/ReleaseNote82[8.2 Release Notes] for an overview of the main new features of Solr 8.2.
+
+When upgrading to 8.2.x, users should be aware of the following major changes from v8.1.
+
+*ZooKeeper 3.5.5*
+
+Solr 8.2 updates the version of ZooKeeper included with Solr to v3.5.5.
+
+It is recommended that external ensembles set up to work with Solr also be updated to ZooKeeper 3.5.5.
+
+This ZooKeeper release includes many new security features.
+In order for Solr's Admin UI to work with 3.5.5, the `zoo.cfg` file must allow access to ZooKeeper's "four-letter commands".
+At a minimum, `ruok`, `conf`, and `mntr` must be enabled, but other commands can optionally be enabled if you choose.
+See the section <<setting-up-an-external-zookeeper-ensemble.adoc#configuration-for-a-zookeeper-ensemble,Configuration for a ZooKeeper Ensemble>> for details.
+
+[WARNING]
+Until 8.3, https://issues.apache.org/jira/browse/SOLR-13672[SOLR-13672] causes the ZK Status screen in the Admin UI to not be able to report status. This only impacts the UI, ZooKeeper still operates correctly.
+
+*Routed Aliases*
+
+* Routed aliases now use collection properties to identify collections that belong to the alias; prior to 8.2, these aliases used core properties.
++
+This is backward-compatible and aliases created with prior versions will
+ continue to work. However, new collections will no longer add the
+ `routedAliasName` property to the `core.properties` file so any external code
+ depending on this location will need to be updated.
+
+// TODO: aliases.adoc still says this is per-core?
+
+* Time-routed aliases now include a `TRA` infix in the collection name, in the pattern `<alias>_TRA_<timestamp>`. +
+Collections created with older versions will continue to work.
+
+*Distributed Tracing Support*
+
+This release adds support for tracing requests in Solr. Please review the section <<solr-tracing.adoc#solr-tracing,Distributed Solr Tracing>> for details on how to configure this feature.
+
=== Solr 8.1
See the https://wiki.apache.org/solr/ReleaseNote810[8.1 Release Notes] for an overview of the main new features of Solr 8.1.
