- Support profile API endpoints on workers ([\#3659](https://github.com/matrix-org/synapse/issues/3659))
- Server notices for resource limit blocking ([\#3680](https://github.com/matrix-org/synapse/issues/3680))
- Allow guests to use /rooms/:roomId/event/:eventId ([\#3724](https://github.com/matrix-org/synapse/issues/3724))
- Add mau_trial_days config param, so that users only get counted as MAU after N days. ([\#3749](https://github.com/matrix-org/synapse/issues/3749))
- Require twisted 17.1 or later (fixes [#3741](https://github.com/matrix-org/synapse/issues/3741)). ([\#3751](https://github.com/matrix-org/synapse/issues/3751))
Bugfixes
--------
- Fix error collecting prometheus metrics when run on dedicated thread due to threading concurrency issues ([\#3722](https://github.com/matrix-org/synapse/issues/3722))
- Fix bug where we resent "limit exceeded" server notices repeatedly ([\#3747](https://github.com/matrix-org/synapse/issues/3747))
- Fix bug where we broke sync when using limit_usage_by_mau but hadn't configured server notices ([\#3753](https://github.com/matrix-org/synapse/issues/3753))
- Fix 'federation_domain_whitelist' such that an empty list correctly blocks all outbound federation traffic ([\#3754](https://github.com/matrix-org/synapse/issues/3754))
- Fix tagging of server notice rooms ([\#3755](https://github.com/matrix-org/synapse/issues/3755), [\#3756](https://github.com/matrix-org/synapse/issues/3756))
- Fix 'admin_uri' config variable and error parameter to be 'admin_contact' to match the spec. ([\#3758](https://github.com/matrix-org/synapse/issues/3758))
- Don't return non-LL-member state in incremental sync state blocks ([\#3760](https://github.com/matrix-org/synapse/issues/3760))
- Fix bug in sending presence over federation ([\#3768](https://github.com/matrix-org/synapse/issues/3768))
- Fix bug where preserved threepid user comes to sign up and server is mau blocked ([\#3777](https://github.com/matrix-org/synapse/issues/3777))
Internal Changes
----------------
- Removed the link to the unmaintained matrix-synapse-auto-deploy project from the readme. ([\#3378](https://github.com/matrix-org/synapse/issues/3378))
- Refactor state module to support multiple room versions ([\#3673](https://github.com/matrix-org/synapse/issues/3673))
- The synapse.storage module has been ported to Python 3. ([\#3725](https://github.com/matrix-org/synapse/issues/3725))
- Split the state_group_cache into member and non-member state events (and so speed up LL /sync) ([\#3726](https://github.com/matrix-org/synapse/issues/3726))
- Log failure to authenticate remote servers as warnings (without stack traces) ([\#3727](https://github.com/matrix-org/synapse/issues/3727))
- The CONTRIBUTING guidelines have been updated to mention our use of Markdown and that .misc files have content. ([\#3730](https://github.com/matrix-org/synapse/issues/3730))
- Reference the need for an HTTP replication port when using the federation_reader worker ([\#3734](https://github.com/matrix-org/synapse/issues/3734))
- Fix minor spelling error in federation client documentation. ([\#3735](https://github.com/matrix-org/synapse/issues/3735))
- Remove redundant state resolution function ([\#3737](https://github.com/matrix-org/synapse/issues/3737))
- The test suite now passes on PostgreSQL. ([\#3740](https://github.com/matrix-org/synapse/issues/3740))
- Fix MAU cache invalidation due to missing yield ([\#3746](https://github.com/matrix-org/synapse/issues/3746))
- Make sure that we close db connections opened during init ([\#3764](https://github.com/matrix-org/synapse/issues/3764))