Today we released updated versions of both the Oppia server and app.
The latest version of the server is v0.12.0 and it quite a big change since now we have moved to using Python 3 and Django 2 (primarily because support for Python 2.x will be dropped at the end of this year).
Since there are a lot of changes, the upgrade process is more complex than our previous releases have been, but we have some (hopefully) complete instructions here: https://oppiamobile.readthedocs.io/en/latest/technical/releases/server/upgrading/to_0_12_0.html
On the app side (now at v6.9.0), the changes are relatively minor, some small refactoring and bug fixes.
The code on the master branches of both the server and app are up to date with server v0.12.0 and app v6.9.0, and the full release notes on the issues fixed can be found at: https://oppiamobile.readthedocs.io/en/latest/technical/releases/server/changelog_server_v0.12.html#v0-12-0-released-17-sept-2019 and https://oppiamobile.readthedocs.io/en/latest/technical/releases/app/changelog_android_v6.html#v69-6-9-0-released-17-sept-2019
Any feedback welcome, and if you find any issues then please let us know.