-The permission model has changed such that all role groups are visible to all active users. This enables users to share objects with groups they don't belong to. To preserve the previous behavior, where role groups are only visible to members and admins, add @RoleGroupsVisibleToAll: false@ to the @Users@ section of your configuration file.
+Ubuntu 18.04 ships with Python 3.6 as the default version of Python 3. Ubuntu also ships a version of Python 3.8, and the Arvados Python packages (@python3-arvados-cwl-runner@, @python3-arvados-fuse@, @python3-arvados-python-client@, @python3-arvados-user-activity@ and @python3-crunchstat-summary@) now depend on the @python-3.8@ system package.
+
+This means that they are now installed under @/usr/share/python3.8@ (before, the path was @/usr/share/python3@). If you rely on the @python3@ executable from the packages (e.g. to load a virtualenv), you may need to update the path to that executable.
+
+h3. Minimum supported Ruby version is now 2.6
+
+The minimum supported Ruby version is now 2.6. If you are running Arvados on Debian 10 or Ubuntu 18.04, you may need to switch to using RVM or upgrade your OS. See "Install Ruby and Bundler":../install/ruby.html for more information.
+
+h3. Anonymous token changes
+
+The anonymous token configured in @Users.AnonymousUserToken@ must now be 32 characters or longer. This was already the suggestion in the documentation, now it is enforced. The @script/get_anonymous_user_token.rb@ script that was needed to register the anonymous user token in the database has been removed. Registration of the anonymous token is no longer necessary.
+
+h3. Preemptible instance support changes
+
+The @Containers.UsePreemptibleInstances@ option has been renamed to @Containers.AlwaysUsePreemptibleInstances@ and has the same behavior when @true@ and one or more preemptible instances are configured. However, a value of @false@ no longer disables support for preemptible instances, instead users can now enable use of preemptible instances at the level of an individual workflow or workflow step.
+
+In addition, there is a new configuration option @Containers.PreemptiblePriceFactor@ will automatically add a preemptible instance type corresponding to each regular instance type. See "Using Preemptible instances":spot-instances.html for details.