==============================

This release removes support for the non-standard feature known both as 'groups' and as 'communities', which have been superseded by *Spaces*.

Features
--------

- Add new `media_retention` options to the homeserver config for routinely cleaning up non-recently accessed media. ([\#12732](https://github.com/matrix-org/synapse/issues/12732), [\#12972](https://github.com/matrix-org/synapse/issues/12972), [\#12977](https://github.com/matrix-org/synapse/issues/12977))
- Experimental support for [MSC3772](https://github.com/matrix-org/matrix-spec-proposals/pull/3772): Push rule for mutually related events. ([\#12740](https://github.com/matrix-org/synapse/issues/12740), [\#12859](https://github.com/matrix-org/synapse/issues/12859))
- Update to the `check_event_for_spam` module callback: Deprecate the current callback signature, replace it with a new signature that is both less ambiguous (replacing booleans with explicit allow/block) and more powerful (ability to return explicit error codes). ([\#12808](https://github.com/matrix-org/synapse/issues/12808))
- Add storage and module API methods to get monthly active users (and their corresponding appservices) within an optionally specified time range. ([\#12838](https://github.com/matrix-org/synapse/issues/12838), [\#12917](https://github.com/matrix-org/synapse/issues/12917))
- Support the new error code `ORG.MATRIX.MSC3823.USER_ACCOUNT_SUSPENDED` from [MSC3823](https://github.com/matrix-org/matrix-spec-proposals/pull/3823). ([\#12845](https://github.com/matrix-org/synapse/issues/12845), [\#12923](https://github.com/matrix-org/synapse/issues/12923))
- Add a configurable background job to delete stale devices. ([\#12855](https://github.com/matrix-org/synapse/issues/12855))
- Improve URL previews for pages with empty elements. ([\#12951](https://github.com/matrix-org/synapse/issues/12951))
- Allow updating a user's password using the admin API without logging out their devices. Contributed by @jcgruenhage. ([\#12952](https://github.com/matrix-org/synapse/issues/12952))

Bugfixes
--------

- Always send an `access_token` in `/thirdparty/` requests to appservices, as required by the [Application Service API specification](https://spec.matrix.org/v1.1/application-service-api/#third-party-networks). ([\#12746](https://github.com/matrix-org/synapse/issues/12746))
- Implement [MSC3816](https://github.com/matrix-org/matrix-spec-proposals/pull/3816): sending the root event in a thread should count as having 'participated' in it. ([\#12766](https://github.com/matrix-org/synapse/issues/12766))
- Delete events from the `federation_inbound_events_staging` table when a room is purged through the admin API. ([\#12784](https://github.com/matrix-org/synapse/issues/12784))
- Fix a bug where we did not correctly handle invalid device list updates over federation. Contributed by Carl Bordum Hansen. ([\#12829](https://github.com/matrix-org/synapse/issues/12829))
- Fix a bug which allowed multiple async operations to access database locks concurrently. Contributed by @sumnerevans @ Beeper. ([\#12832](https://github.com/matrix-org/synapse/issues/12832))
- Fix an issue introduced in Synapse 0.34 where the `/notifications` endpoint would only return notifications if a user registered at least one pusher. Contributed by Famedly. ([\#12840](https://github.com/matrix-org/synapse/issues/12840))
- Fix a bug where servers using a Postgres database would fail to backfill from an insertion event when MSC2716 is enabled (`experimental_features.msc2716_enabled`). ([\#12843](https://github.com/matrix-org/synapse/issues/12843))
- Fix [MSC3787](https://github.com/matrix-org/matrix-spec-proposals/pull/3787) rooms being omitted from room directory, room summary and space hierarchy responses. ([\#12858](https://github.com/matrix-org/synapse/issues/12858))
- Fix a bug introduced in Synapse 1.54.0 which could sometimes cause exceptions when handling federated traffic. ([\#12877](https://github.com/matrix-org/synapse/issues/12877))
- Fix a bug introduced in Synapse 1.59.0 which caused room deletion to fail with a foreign key violation error. ([\#12889](https://github.com/matrix-org/synapse/issues/12889))
- Fix a long-standing bug which caused the `/messages` endpoint to return an incorrect `end` attribute when there were no more events. Contributed by @Vetchu. ([\#12903](https://github.com/matrix-org/synapse/issues/12903))
- Fix a bug introduced in Synapse 1.58.0 where `/sync` would fail if the most recent event in a room was a redaction of an event that has since been purged. ([\#12905](https://github.com/matrix-org/synapse/issues/12905))
- Fix a potential memory leak when generating thumbnails. ([\#12932](https://github.com/matrix-org/synapse/issues/12932))
- Fix a long-standing bug where a URL preview would break if the image failed to download. ([\#12950](https://github.com/matrix-org/synapse/issues/12950))

Improved Documentation
----------------------

- Fix typographical errors in documentation. ([\#12863](https://github.com/matrix-org/synapse/issues/12863))
- Fix documentation incorrectly stating the `sendToDevice` endpoint can be directed at generic workers. Contributed by Nick @ Beeper. ([\#12867](https://github.com/matrix-org/synapse/issues/12867))

Deprecations and Removals
-------------------------

- Remove support for the non-standard groups/communities feature from Synapse. ([\#12553](https://github.com/matrix-org/synapse/issues/12553), [\#12558](https://github.com/matrix-org/synapse/issues/12558), [\#12563](https://github.com/matrix-org/synapse/issues/12563), [\#12895](https://github.com/matrix-org/synapse/issues/12895), [\#12897](https://github.com/matrix-org/synapse/issues/12897), [\#12899](https://github.com/matrix-org/synapse/issues/12899), [\#12900](https://github.com/matrix-org/synapse/issues/12900), [\#12936](https://github.com/matrix-org/synapse/issues/12936), [\#12966](https://github.com/matrix-org/synapse/issues/12966))
- Remove contributed `kick_users.py` script. This is broken under Python 3, and is not added to the environment when `pip install`ing Synapse. ([\#12908](https://github.com/matrix-org/synapse/issues/12908))
- Remove `contrib/jitsimeetbridge`. This was an unused experiment that hasn't been meaningfully changed since 2014. ([\#12909](https://github.com/matrix-org/synapse/issues/12909))
- Remove unused `contrib/experiements/cursesio.py` script, which fails to run under Python 3. ([\#12910](https://github.com/matrix-org/synapse/issues/12910))
- Remove unused `contrib/experiements/test_messaging.py` script. This fails to run on Python 3. ([\#12911](https://github.com/matrix-org/synapse/issues/12911))

Internal Changes
----------------

- Test Synapse against Complement with workers. ([\#12810](https://github.com/matrix-org/synapse/issues/12810), [\#12933](https://github.com/matrix-org/synapse/issues/12933))
- Reduce the amount of state we pull from the DB. ([\#12811](https://github.com/matrix-org/synapse/issues/12811), [\#12964](https://github.com/matrix-org/synapse/issues/12964))
- Try other homeservers when re-syncing state for rooms with partial state. ([\#12812](https://github.com/matrix-org/synapse/issues/12812))
- Resume state re-syncing for rooms with partial state after a Synapse restart. ([\#12813](https://github.com/matrix-org/synapse/issues/12813))
- Remove Mutual Rooms' ([MSC2666](https://github.com/matrix-org/matrix-spec-proposals/pull/2666)) endpoint dependency on the User Directory. ([\#12836](https://github.com/matrix-org/synapse/issues/12836))
- Experimental: expand `check_event_for_spam` with ability to return additional fields. This enables spam-checker implementations to experiment with mechanisms to give users more information about why they are blocked and whether any action is needed from them to be unblocked. ([\#12846](https://github.com/matrix-org/synapse/issues/12846))
- Remove `dont_notify` from the `.m.rule.room.server_acl` rule. ([\#12849](https://github.com/matrix-org/synapse/issues/12849))
- Remove the unstable `/hierarchy` endpoint from [MSC2946](https://github.com/matrix-org/matrix-doc/pull/2946). ([\#12851](https://github.com/matrix-org/synapse/issues/12851))
- Pull out less state when handling gaps in room DAG. ([\#12852](https://github.com/matrix-org/synapse/issues/12852), [\#12904](https://github.com/matrix-org/synapse/issues/12904))
- Clean-up the push rules datastore. ([\#12856](https://github.com/matrix-org/synapse/issues/12856))
- Correct a type annotation in the URL preview source code. ([\#12860](https://github.com/matrix-org/synapse/issues/12860))
- Update `pyjwt` dependency to [2.4.0](https://github.com/jpadilla/pyjwt/releases/tag/2.4.0). ([\#12865](https://github.com/matrix-org/synapse/issues/12865))
- Enable the `/account/whoami` endpoint on synapse worker processes. Contributed by Nick @ Beeper. ([\#12866](https://github.com/matrix-org/synapse/issues/12866))
- Enable the `batch_send` endpoint on synapse worker processes. Contributed by Nick @ Beeper. ([\#12868](https://github.com/matrix-org/synapse/issues/12868))
- Don't generate empty AS transactions when the AS is flagged as down. Contributed by Nick @ Beeper. ([\#12869](https://github.com/matrix-org/synapse/issues/12869))
- Fix up the variable `state_store` naming. ([\#12871](https://github.com/matrix-org/synapse/issues/12871))
- Faster room joins: when querying the current state of the room, wait for state to be populated. ([\#12872](https://github.com/matrix-org/synapse/issues/12872))
- Avoid running queries which will never result in deletions. ([\#12879](https://github.com/matrix-org/synapse/issues/12879))
- Use constants for EDU types. ([\#12884](https://github.com/matrix-org/synapse/issues/12884))
- Reduce database load of `/sync` when presence is enabled. ([\#12885](https://github.com/matrix-org/synapse/issues/12885))
- Refactor `have_seen_events` to reduce memory consumed when processing federation traffic. ([\#12886](https://github.com/matrix-org/synapse/issues/12886))
- Refactor receipt linearization code. ([\#12888](https://github.com/matrix-org/synapse/issues/12888))
- Add type annotations to `synapse.logging.opentracing`. ([\#12894](https://github.com/matrix-org/synapse/issues/12894))
- Remove PyNaCl occurrences directly used in Synapse code. ([\#12902](https://github.com/matrix-org/synapse/issues/12902))
- Bump types-jsonschema from 4.4.1 to 4.4.6. ([\#12912](https://github.com/matrix-org/synapse/issues/12912))
- Rename storage classes. ([\#12913](https://github.com/matrix-org/synapse/issues/12913))
- Preparation for database schema simplifications: stop reading from `event_edges.room_id`. ([\#12914](https://github.com/matrix-org/synapse/issues/12914))
- Check if we are in a virtual environment before overriding the `PYTHONPATH` environment variable in the demo script. ([\#12916](https://github.com/matrix-org/synapse/issues/12916))
- Improve the logging when signature checks on events fail. ([\#12925](https://github.com/matrix-org/synapse/issues/12925))