+h3. arvados-login-sync configuration changes, including ignored groups
+
+In the @Users@ section of your cluster configuration, there are now several options to control what system resources are or are not managed by @arvados-login-sync@. These options all have names that begin with @Sync@.
+
+The defaults for all of these options match the previous behavior of @arvados-login-sync@ _except_ for @SyncIgnoredGroups@. This list names groups that @arvados-login-sync@ will never modify by adding or removing members. As a security precaution, the default list names security-sensitive system groups on Debian- and Red Hat-based distributions. If you are using Arvados to manage system group membership on shell nodes, especially @sudo@ or @wheel@, you may want to provide your own list. Set @SyncIgnoredGroups: []@ to restore the original behavior of ignoring no groups.
+
+h3. UseAWSS3v2Driver option removed
+
+The old "v1" S3 driver for keepstore has been removed. The new "v2" implementation, which has been the default since Arvados 2.5.0, is always used. The @Volumes.*.DriverParameters.UseAWSS3v2Driver@ configuration key is no longer recognized. If your config file uses it, remove it to avoid warning messages at startup.
+
+h2(#v2_6_3). v2.6.3 (2023-06-06)
+