Features
--------

- Python 3.5 and 3.6 support is now in beta.
([\#3576](https://github.com/matrix-org/synapse/issues/3576))
- Implement `event_format` filter param in `/sync`
([\#3790](https://github.com/matrix-org/synapse/issues/3790))
- Add synapse_admin_mau:registered_reserved_users metric to expose
number of real reaserved users
([\#3846](https://github.com/matrix-org/synapse/issues/3846))

Bugfixes
--------

- Remove connection ID for replication prometheus metrics, as it creates
a large number of new series.
([\#3788](https://github.com/matrix-org/synapse/issues/3788))
- guest users should not be part of mau total
([\#3800](https://github.com/matrix-org/synapse/issues/3800))
- Bump dependency on pyopenssl 16.x, to avoid incompatibility with
recent Twisted.
([\#3804](https://github.com/matrix-org/synapse/issues/3804))
- Fix existing room tags not coming down sync when joining a room
([\#3810](https://github.com/matrix-org/synapse/issues/3810))
- Fix jwt import check
([\#3824](https://github.com/matrix-org/synapse/issues/3824))
- fix VOIP crashes under Python 3 (#3821)
([\#3835](https://github.com/matrix-org/synapse/issues/3835))
- Fix manhole so that it works with latest openssh clients
([\#3841](https://github.com/matrix-org/synapse/issues/3841))
- Fix outbound requests occasionally wedging, which can result in
federation breaking between servers.
([\#3845](https://github.com/matrix-org/synapse/issues/3845))
- Show heroes if room name/canonical alias has been deleted
([\#3851](https://github.com/matrix-org/synapse/issues/3851))
- Fix handling of redacted events from federation
([\#3859](https://github.com/matrix-org/synapse/issues/3859))
-  ([\#3874](https://github.com/matrix-org/synapse/issues/3874))
- Mitigate outbound federation randomly becoming wedged
([\#3875](https://github.com/matrix-org/synapse/issues/3875))

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

- CircleCI tests now run on the potential merge of a PR.
([\#3704](https://github.com/matrix-org/synapse/issues/3704))
- http/ is now ported to Python 3.
([\#3771](https://github.com/matrix-org/synapse/issues/3771))
- Improve human readable error messages for threepid
registration/account update
([\#3789](https://github.com/matrix-org/synapse/issues/3789))
- Make /sync slightly faster by avoiding needless copies
([\#3795](https://github.com/matrix-org/synapse/issues/3795))
- handlers/ is now ported to Python 3.
([\#3803](https://github.com/matrix-org/synapse/issues/3803))
- Limit the number of PDUs/EDUs per federation transaction
([\#3805](https://github.com/matrix-org/synapse/issues/3805))
- Only start postgres instance for postgres tests on Travis CI
([\#3806](https://github.com/matrix-org/synapse/issues/3806))
- tests/ is now ported to Python 3.
([\#3808](https://github.com/matrix-org/synapse/issues/3808))
- crypto/ is now ported to Python 3.
([\#3822](https://github.com/matrix-org/synapse/issues/3822))
- rest/ is now ported to Python 3.
([\#3823](https://github.com/matrix-org/synapse/issues/3823))
- add some logging for the keyring queue
([\#3826](https://github.com/matrix-org/synapse/issues/3826))
- speed up lazy loading by 2-3x
([\#3827](https://github.com/matrix-org/synapse/issues/3827))
- Improved Dockerfile to remove build requirements after building
reducing the image size.
([\#3834](https://github.com/matrix-org/synapse/issues/3834))
- Disable lazy loading for incremental syncs for now
([\#3840](https://github.com/matrix-org/synapse/issues/3840))
- federation/ is now ported to Python 3.
([\#3847](https://github.com/matrix-org/synapse/issues/3847))
- Log when we retry outbound requests
([\#3853](https://github.com/matrix-org/synapse/issues/3853))
- Removed some excess logging messages.
([\#3855](https://github.com/matrix-org/synapse/issues/3855))
- Speed up purge history for rooms that have been previously purged
([\#3856](https://github.com/matrix-org/synapse/issues/3856))
- Refactor some HTTP timeout code.
([\#3857](https://github.com/matrix-org/synapse/issues/3857))
- Fix running merged builds on CircleCI
([\#3858](https://github.com/matrix-org/synapse/issues/3858))
- Fix typo in replication stream exception.
([\#3860](https://github.com/matrix-org/synapse/issues/3860))
- Add in flight real time metrics for Measure blocks
([\#3871](https://github.com/matrix-org/synapse/issues/3871))
- Disable buffering and automatic retrying in treq requests to prevent
timeouts. ([\#3872](https://github.com/matrix-org/synapse/issues/3872))
- mention jemalloc in the README
([\#3877](https://github.com/matrix-org/synapse/issues/3877))
- Remove unmaintained "nuke-room-from-db.sh" script
([\#3888](https://github.com/matrix-org/synapse/issues/3888))
This tag has no release notes.