upgrade.md

# Upgrading Synapse

Before upgrading check if any special steps are required to upgrade from
the version you currently have installed to the current version of
Synapse. The extra instructions that may be required are listed later in
this document.

-   Check that your versions of Python and PostgreSQL are still
    supported.

    Synapse follows upstream lifecycles for [Python](https://endoflife.date/python) and
    [PostgreSQL](https://endoflife.date/postgresql), and removes support for versions
    which are no longer maintained.

    The website <https://endoflife.date> also offers convenient
    summaries.

-   If Synapse was installed using [prebuilt packages](setup/installation.md#prebuilt-packages),
    you will need to follow the normal process for upgrading those packages.

-   If Synapse was installed using pip then upgrade to the latest
    version by running:

    ```bash
    pip install --upgrade matrix-synapse
    ```

-   If Synapse was installed from source, then:

    1.  Obtain the latest version of the source code. Git users can run
        `git pull` to do this.

    2.  If you're running Synapse in a virtualenv, make sure to activate it before
        upgrading. For example, if Synapse is installed in a virtualenv in `~/synapse/env` then
        run:

        ```bash
        source ~/synapse/env/bin/activate
        pip install --upgrade .
        ```
        Include any relevant extras between square brackets, e.g. `pip install --upgrade ".[postgres,oidc]"`.

    3.  If you're using `poetry` to manage a Synapse installation, run:
        ```bash
        poetry install
        ```
        Include any relevant extras with `--extras`, e.g. `poetry install --extras postgres --extras oidc`.
        It's probably easiest to run `poetry install --extras all`.

    4.  Restart Synapse:

        ```bash
        synctl restart
        ```

To check whether your update was successful, you can check the running
server version with:

```bash
# you may need to replace 'localhost:8008' if synapse is not configured
# to listen on port 8008.

curl http://localhost:8008/_synapse/admin/v1/server_version
```

## Rolling back to older versions

Rolling back to previous releases can be difficult, due to database
schema changes between releases. Where we have been able to test the
rollback process, this will be noted below.

In general, you will need to undo any changes made during the upgrade
process, for example:

-   pip:

    ```bash
    source env/bin/activate
    # replace `1.3.0` accordingly:
    pip install matrix-synapse==1.3.0
    ```

-   Debian:

    ```bash
    # replace `1.3.0` and `stretch` accordingly:
    wget https://packages.matrix.org/debian/pool/main/m/matrix-synapse-py3/matrix-synapse-py3_1.3.0+stretch1_amd64.deb
    dpkg -i matrix-synapse-py3_1.3.0+stretch1_amd64.deb
    ```

# Upgrading to v1.93.0

## Minimum supported Rust version
The minimum supported Rust version has been increased from v1.60.0 to v1.61.0.
Users building from source will need to ensure their `rustc` version is up to
date.


# Upgrading to v1.90.0

## App service query parameter authorization is now a configuration option

Synapse v1.81.0 deprecated application service authorization via query parameters as this is
considered insecure - and from Synapse v1.71.0 forwards the application service token has also been sent via 
[the `Authorization` header](https://spec.matrix.org/v1.6/application-service-api/#authorization)], making the insecure
query parameter authorization redundant. Since removing the ability to continue to use query parameters could break 
backwards compatibility it has now been put behind a configuration option, `use_appservice_legacy_authorization`.  
This option defaults to false, but can be activated by adding 
```yaml
use_appservice_legacy_authorization: true 
```
to your configuration.

# Upgrading to v1.89.0

## Removal of unspecced `user` property for `/register`

Application services can no longer call `/register` with a `user` property to create new users.
The standard `username` property should be used instead. See the
[Application Service specification](https://spec.matrix.org/v1.7/application-service-api/#server-admin-style-permissions)
for more information.

# Upgrading to v1.88.0

## Minimum supported Python version

The minimum supported Python version has been increased from v3.7 to v3.8.
You will need Python 3.8 to run Synapse v1.88.0 (due out July 18th, 2023).

If you use current versions of the Matrix.org-distributed Debian
packages or Docker images, no action is required.

## Removal of `worker_replication_*` settings

As mentioned previously in [Upgrading to v1.84.0](#upgrading-to-v1840), the following deprecated settings
are being removed in this release of Synapse:

* [`worker_replication_host`](https://matrix-org.github.io/synapse/v1.86/usage/configuration/config_documentation.html#worker_replication_host)
* [`worker_replication_http_port`](https://matrix-org.github.io/synapse/v1.86/usage/configuration/config_documentation.html#worker_replication_http_port)
* [`worker_replication_http_tls`](https://matrix-org.github.io/synapse/v1.86/usage/configuration/config_documentation.html#worker_replication_http_tls)

Please ensure that you have migrated to using `main` on your shared configuration's `instance_map`
(or create one if necessary). This is required if you have ***any*** workers at all;
administrators of single-process (monolith) installations don't need to do anything.

For an illustrative example, please see [Upgrading to v1.84.0](#upgrading-to-v1840) below.


# Upgrading to v1.86.0

## Minimum supported Rust version

The minimum supported Rust version has been increased from v1.58.1 to v1.60.0.
Users building from source will need to ensure their `rustc` version is up to
date.


# Upgrading to v1.85.0

## Application service registration with "user" property deprecation

Application services should ensure they call the `/register` endpoint with a
`username` property. The legacy `user` property is considered deprecated and
should no longer be included.

A future version of Synapse (v1.88.0 or later) will remove support for legacy
application service login.

# Upgrading to v1.84.0

## Deprecation of `worker_replication_*` configuration settings

When using workers,

* `worker_replication_host`
* `worker_replication_http_port`
* `worker_replication_http_tls`
 
should now be removed from individual worker YAML configurations and the main process should instead be added to the `instance_map`
in the shared YAML configuration, using the name `main`.

The old `worker_replication_*` settings are now considered deprecated and are expected to be removed in Synapse v1.88.0.


### Example change

#### Before:

Shared YAML
```yaml
instance_map:
  generic_worker1:
    host: localhost
    port: 5678
    tls: false
```

Worker YAML
```yaml
worker_app: synapse.app.generic_worker
worker_name: generic_worker1

worker_replication_host: localhost
worker_replication_http_port: 3456
worker_replication_http_tls: false

worker_listeners:
  - type: http
    port: 1234
    resources:
      - names: [client, federation]
  - type: http
    port: 5678
    resources:
      - names: [replication]

worker_log_config: /etc/matrix-synapse/generic-worker-log.yaml
```


#### After:

Shared YAML
```yaml
instance_map:
  main:
    host: localhost
    port: 3456
    tls: false
  generic_worker1:
    host: localhost
    port: 5678
    tls: false
```

Worker YAML
```yaml
worker_app: synapse.app.generic_worker
worker_name: generic_worker1

worker_listeners:
  - type: http
    port: 1234
    resources:
      - names: [client, federation]
  - type: http
    port: 5678
    resources:
      - names: [replication]

worker_log_config: /etc/matrix-synapse/generic-worker-log.yaml

```
Notes: 
* `tls` is optional but mirrors the functionality of `worker_replication_http_tls`


# Upgrading to v1.81.0

## Application service path & authentication deprecations

Synapse now attempts the versioned appservice paths before falling back to the
[legacy paths](https://spec.matrix.org/v1.6/application-service-api/#legacy-routes).
Usage of the legacy routes should be considered deprecated.

Additionally, Synapse has supported sending the application service access token
via [the `Authorization` header](https://spec.matrix.org/v1.6/application-service-api/#authorization)
since v1.70.0. For backwards compatibility it is *also* sent as the `access_token`
query parameter. This is insecure and should be considered deprecated.

A future version of Synapse (v1.88.0 or later) will remove support for legacy
application service routes and query parameter authorization.

# Upgrading to v1.80.0

## Reporting events error code change

Before this update, the
[`POST /_matrix/client/v3/rooms/{roomId}/report/{eventId}`](https://spec.matrix.org/v1.6/client-server-api/#post_matrixclientv3roomsroomidreporteventid)
endpoint would return a `403` if a user attempted to report an event that they did not have access to.
This endpoint will now return a `404` in this case instead.

Clients that implement event reporting should check that their error handling code will handle this
change.

# Upgrading to v1.79.0

## The `on_threepid_bind` module callback method has been deprecated

Synapse v1.79.0 deprecates the
[`on_threepid_bind`](modules/third_party_rules_callbacks.md#on_threepid_bind)
"third-party rules" Synapse module callback method in favour of a new module method,
[`on_add_user_third_party_identifier`](modules/third_party_rules_callbacks.md#on_add_user_third_party_identifier).
`on_threepid_bind` will be removed in a future version of Synapse. You should check whether any Synapse
modules in use in your deployment are making use of `on_threepid_bind`, and update them where possible.

The arguments and functionality of the new method are the same.

The justification behind the name change is that the old method's name, `on_threepid_bind`, was
misleading. A user is considered to "bind" their third-party ID to their Matrix ID only if they
do so via an [identity server](https://spec.matrix.org/latest/identity-service-api/)
(so that users on other homeservers may find them). But this method was not called in that case -
it was only called when a user added a third-party identifier on the local homeserver.

Module developers may also be interested in the related
[`on_remove_user_third_party_identifier`](modules/third_party_rules_callbacks.md#on_remove_user_third_party_identifier)
module callback method that was also added in Synapse v1.79.0. This new method is called when a
user removes a third-party identifier from their account.

# Upgrading to v1.78.0

## Deprecate the `/_synapse/admin/v1/media/<server_name>/delete` admin API

Synapse 1.78.0 replaces the `/_synapse/admin/v1/media/<server_name>/delete`
admin API with an identical endpoint at `/_synapse/admin/v1/media/delete`. Please
update your tooling to use the new endpoint. The deprecated version will be removed
in a future release.

# Upgrading to v1.76.0

## Faster joins are enabled by default

When joining a room for the first time, Synapse 1.76.0 will request a partial join from the other server by default. Previously, server admins had to opt-in to this using an experimental config flag.

Server admins can opt out of this feature for the time being by setting

```yaml
experimental:
    faster_joins: false
```

in their server config.

## Changes to the account data replication streams

Synapse has changed the format of the account data and devices replication
streams (between workers). This is a forwards- and backwards-incompatible
change: v1.75 workers cannot process account data replicated by v1.76 workers,
and vice versa.

Once all workers are upgraded to v1.76 (or downgraded to v1.75), account data
and device replication will resume as normal.

## Minimum version of Poetry is now 1.3.2

The minimum supported version of Poetry is now 1.3.2 (previously 1.2.0, [since 
Synapse 1.67](#upgrading-to-v1670)). If you have used `poetry install` to 
install Synapse from a source checkout, you should upgrade poetry: see its
[installation instructions](https://python-poetry.org/docs/#installation).
For all other installation methods, no acction is required.

# Upgrading to v1.74.0

## Unicode support in user search

This version introduces optional support for an [improved user search dealing with Unicode characters](https://github.com/matrix-org/synapse/pull/14464).

If you want to take advantage of this feature you need to install PyICU,
the ICU native dependency and its development headers
so that PyICU can build since no prebuilt wheels are available.

You can follow [the PyICU documentation](https://pypi.org/project/PyICU/) to do so,
and then do `pip install matrix-synapse[user-search]` for a PyPI install.

Docker images and Debian packages need nothing specific as they already
include or specify ICU as an explicit dependency.


## User directory rebuild

Synapse 1.74 queues a background update
[to rebuild the user directory](https://github.com/matrix-org/synapse/pull/14643),
in order to fix missing or erroneous entries.

When this update begins, the user directory will be cleared out and rebuilt from
scratch. User directory lookups will be incomplete until the rebuild completes.
Admins can monitor the rebuild's progress by using the
[Background update Admin API](usage/administration/admin_api/background_updates.md#status).

# Upgrading to v1.73.0

## Legacy Prometheus metric names have now been removed

Synapse v1.69.0 included the deprecation of legacy Prometheus metric names
and offered an option to disable them.
Synapse v1.71.0 disabled legacy Prometheus metric names by default.

This version, v1.73.0, removes those legacy Prometheus metric names entirely.
This also means that the `enable_legacy_metrics` configuration option has been
removed; it will no longer be possible to re-enable the legacy metric names.

If you use metrics and have not yet updated your Grafana dashboard(s),
Prometheus console(s) or alerting rule(s), please consider doing so when upgrading
to this version.
Note that the included Grafana dashboard was updated in v1.72.0 to correct some
metric names which were missed when legacy metrics were disabled by default.

See [v1.69.0: Deprecation of legacy Prometheus metric names](#deprecation-of-legacy-prometheus-metric-names)
for more context.


# Upgrading to v1.72.0

## Dropping support for PostgreSQL 10

In line with our [deprecation policy](deprecation_policy.md), we've dropped
support for PostgreSQL 10, as it is no longer supported upstream.

This release of Synapse requires PostgreSQL 11+.


# Upgrading to v1.71.0

## Removal of the `generate_short_term_login_token` module API method

As announced with the release of [Synapse 1.69.0](#deprecation-of-the-generate_short_term_login_token-module-api-method), the deprecated `generate_short_term_login_token` module method has been removed.

Modules relying on it can instead use the `create_login_token` method.


## Changes to the events received by application services (interest)

To align with spec (changed in
[MSC3905](https://github.com/matrix-org/matrix-spec-proposals/pull/3905)), Synapse now
only considers local users to be interesting. In other words, the `users` namespace
regex is only be applied against local users of the homeserver.

Please note, this probably doesn't affect the expected behavior of your application
service, since an interesting local user in a room still means all messages in the room
(from local or remote users) will still be considered interesting. And matching a room
with the `rooms` or `aliases` namespace regex will still consider all events sent in the
room to be interesting to the application service.

If one of your application service's `users` regex was intending to match a remote user,
this will no longer match as you expect. The behavioral mismatch between matching all
local users and some remote users is why the spec was changed/clarified and this
caveat is no longer supported.


## Legacy Prometheus metric names are now disabled by default

Synapse v1.71.0 disables legacy Prometheus metric names by default.
For administrators that still rely on them and have not yet had chance to update their
uses of the metrics, it's still possible to specify `enable_legacy_metrics: true` in
the configuration to re-enable them temporarily.

Synapse v1.73.0 will **remove legacy metric names altogether** and at that point,
it will no longer be possible to re-enable them.

If you do not use metrics or you have already updated your Grafana dashboard(s),
Prometheus console(s) and alerting rule(s), there is no action needed.

See [v1.69.0: Deprecation of legacy Prometheus metric names](#deprecation-of-legacy-prometheus-metric-names).


# Upgrading to v1.69.0

## Changes to the receipts replication streams

Synapse now includes information indicating if a receipt applies to a thread when
replicating it to other workers. This is a forwards- and backwards-incompatible
change: v1.68 and workers cannot process receipts replicated by v1.69 workers, and
vice versa.

Once all workers are upgraded to v1.69 (or downgraded to v1.68), receipts
replication will resume as normal.


## Deprecation of legacy Prometheus metric names

In current versions of Synapse, some Prometheus metrics are emitted under two different names,
with one of the names being older but non-compliant with OpenMetrics and Prometheus conventions
and one of the names being newer but compliant.

Synapse v1.71.0 will turn the old metric names off *by default*.
For administrators that still rely on them and have not had chance to update their
uses of the metrics, it's possible to specify `enable_legacy_metrics: true` in
the configuration to re-enable them temporarily.

Synapse v1.73.0 will **remove legacy metric names altogether** and it will no longer
be possible to re-enable them.

The Grafana dashboard, Prometheus recording rules and Prometheus Consoles included
in the `contrib` directory in the Synapse repository have been updated to no longer
rely on the legacy names. These can be used on a current version of Synapse
because current versions of Synapse emit both old and new names.

You may need to update your alerting rules or any other rules that depend on
the names of Prometheus metrics.
If you want to test your changes before legacy names are disabled by default,
you may specify `enable_legacy_metrics: false` in your homeserver configuration.

A list of affected metrics is available on the [Metrics How-to page](https://matrix-org.github.io/synapse/v1.69/metrics-howto.html?highlight=metrics%20deprecated#renaming-of-metrics--deprecation-of-old-names-in-12).


## Deprecation of the `generate_short_term_login_token` module API method

The following method of the module API has been deprecated, and is scheduled to
be remove in v1.71.0:

```python
def generate_short_term_login_token(
    self,
    user_id: str,
    duration_in_ms: int = (2 * 60 * 1000),
    auth_provider_id: str = "",
    auth_provider_session_id: Optional[str] = None,
) -> str:
    ...
```

It has been replaced by an asynchronous equivalent:

```python
async def create_login_token(
    self,
    user_id: str,
    duration_in_ms: int = (2 * 60 * 1000),
    auth_provider_id: Optional[str] = None,
    auth_provider_session_id: Optional[str] = None,
) -> str:
    ...
```

Synapse will log a warning when a module uses the deprecated method, to help
administrators find modules using it.


# Upgrading to v1.68.0

Two changes announced in the upgrade notes for v1.67.0 have now landed in v1.68.0.

## SQLite version requirement

Synapse now requires a SQLite version of 3.27.0 or higher if SQLite is configured as
Synapse's database.

Installations using

- Docker images [from `matrixdotorg`](https://hub.docker.com/r/matrixdotorg/synapse),
- Debian packages [from Matrix.org](https://packages.matrix.org/), or
- a PostgreSQL database

are not affected.

## Rust requirement when building from source.

Building from a source checkout of Synapse now requires a recent Rust compiler
(currently Rust 1.58.1, but see also the
[Platform Dependency Policy](https://matrix-org.github.io/synapse/latest/deprecation_policy.html)).

Installations using

- Docker images [from `matrixdotorg`](https://hub.docker.com/r/matrixdotorg/synapse),
- Debian packages [from Matrix.org](https://packages.matrix.org/), or
- PyPI wheels via `pip install matrix-synapse` (on supported platforms and architectures)

will not be affected.

# Upgrading to v1.67.0

## Direct TCP replication is no longer supported: migrate to Redis

Redis support was added in v1.13.0 with it becoming the recommended method in
v1.18.0. It replaced the old direct TCP connections (which was deprecated as of
v1.18.0) to the main process. With Redis, rather than all the workers connecting
to the main process, all the workers and the main process connect to Redis,
which relays replication commands between processes. This can give a significant
CPU saving on the main process and is a prerequisite for upcoming
performance improvements.

To migrate to Redis add the [`redis` config](./workers.md#shared-configuration),
and remove the TCP `replication` listener from config of the master and
`worker_replication_port` from worker config. Note that a HTTP listener with a
`replication` resource is still required.

## Minimum version of Poetry is now v1.2.0

The minimum supported version of poetry is now 1.2. This should only affect
those installing from a source checkout.

## Rust requirement in the next release

From the next major release (v1.68.0) installing Synapse from a source checkout
will require a recent Rust compiler. Those using packages or
`pip install matrix-synapse` will not be affected.

The simplest way of installing Rust is via [rustup.rs](https://rustup.rs/)

## SQLite version requirement in the next release

From the next major release (v1.68.0) Synapse will require SQLite 3.27.0 or
higher. Synapse v1.67.0 will be the last major release supporting SQLite
versions 3.22 to 3.26.

Those using Docker images or Debian packages from Matrix.org will not be
affected. If you have installed from source, you should check the version of
SQLite used by Python with:

```shell
python -c "import sqlite3; print(sqlite3.sqlite_version)"
```

If this is too old, refer to your distribution for advice on upgrading.


# Upgrading to v1.66.0

## Delegation of email validation no longer supported

As of this version, Synapse no longer allows the tasks of verifying email address
ownership, and password reset confirmation, to be delegated to an identity server.
This removal was previously planned for Synapse 1.64.0, but was
[delayed](https://github.com/matrix-org/synapse/issues/13421) until now to give
homeserver administrators more notice of the change.

To continue to allow users to add email addresses to their homeserver accounts,
and perform password resets, make sure that Synapse is configured with a working
email server in the [`email` configuration
section](https://matrix-org.github.io/synapse/latest/usage/configuration/config_documentation.html#email)
(including, at a minimum, a `notif_from` setting.)

Specifying an `email` setting under `account_threepid_delegates` will now cause
an error at startup.

# Upgrading to v1.64.0

## Deprecation of the ability to delegate e-mail verification to identity servers

Synapse v1.66.0 will remove the ability to delegate the tasks of verifying email address ownership, and password reset confirmation, to an identity server.

If you require your homeserver to verify e-mail addresses or to support password resets via e-mail, please configure your homeserver with SMTP access so that it can send e-mails on its own behalf.
[Consult the configuration documentation for more information.](https://matrix-org.github.io/synapse/latest/usage/configuration/config_documentation.html#email)

The option that will be removed is `account_threepid_delegates.email`.


## Changes to the event replication streams

Synapse now includes a flag indicating if an event is an outlier when
replicating it to other workers. This is a forwards- and backwards-incompatible
change: v1.63 and workers cannot process events replicated by v1.64 workers, and
vice versa.

Once all workers are upgraded to v1.64 (or downgraded to v1.63), event
replication will resume as normal.

## frozendict release

[frozendict 2.3.3](https://github.com/Marco-Sulla/python-frozendict/releases/tag/v2.3.3)
has recently been released, which fixes a memory leak that occurs during `/sync`
requests. We advise server administrators who installed Synapse via pip to upgrade
frozendict with `pip install --upgrade frozendict`. The Docker image
`matrixdotorg/synapse` and the Debian packages from `packages.matrix.org` already
include the updated library.

# Upgrading to v1.62.0

## New signatures for spam checker callbacks

As a followup to changes in v1.60.0, the following spam-checker callbacks have changed signature:

- `user_may_join_room`
- `user_may_invite`
- `user_may_send_3pid_invite`
- `user_may_create_room`
- `user_may_create_room_alias`
- `user_may_publish_room`
- `check_media_file_for_spam`

For each of these methods, the previous callback signature has been deprecated.

Whereas callbacks used to return `bool`, they should now return `Union["synapse.module_api.NOT_SPAM", "synapse.module_api.errors.Codes"]`.

For instance, if your module implements `user_may_join_room` as follows:

```python
async def user_may_join_room(self, user_id: str, room_id: str, is_invited: bool)
    if ...:
        # Request is spam
        return False
    # Request is not spam
    return True
```

you should rewrite it as follows:

```python
async def user_may_join_room(self, user_id: str, room_id: str, is_invited: bool)
    if ...:
        # Request is spam, mark it as forbidden (you may use some more precise error
        # code if it is useful).
        return synapse.module_api.errors.Codes.FORBIDDEN
    # Request is not spam, mark it as such.
    return synapse.module_api.NOT_SPAM
```

# Upgrading to v1.61.0

## Removal of deprecated community/groups

This release of Synapse will remove deprecated community/groups from codebase.

### Worker endpoints

For those who have deployed workers, following worker endpoints will no longer
exist and they can be removed from the reverse proxy configuration:

-   `^/_matrix/federation/v1/get_groups_publicised$`
-   `^/_matrix/client/(r0|v3|unstable)/joined_groups$`
-   `^/_matrix/client/(r0|v3|unstable)/publicised_groups$`
-   `^/_matrix/client/(r0|v3|unstable)/publicised_groups/`
-   `^/_matrix/federation/v1/groups/`
-   `^/_matrix/client/(r0|v3|unstable)/groups/`

# Upgrading to v1.60.0

## Adding a new unique index to `state_group_edges` could fail if your database is corrupted

This release of Synapse will add a unique index to the `state_group_edges` table, in order
to prevent accidentally introducing duplicate information (for example, because a database
backup was restored multiple times).

Duplicate rows being present in this table could cause drastic performance problems; see
[issue 11779](https://github.com/matrix-org/synapse/issues/11779) for more details.

If your Synapse database already has had duplicate rows introduced into this table,
this could fail, with either of these errors:


**On Postgres:**
```
synapse.storage.background_updates - 623 - INFO - background_updates-0 - Adding index state_group_edges_unique_idx to state_group_edges
synapse.storage.background_updates - 282 - ERROR - background_updates-0 - Error doing update
...
psycopg2.errors.UniqueViolation: could not create unique index "state_group_edges_unique_idx"
DETAIL:  Key (state_group, prev_state_group)=(2, 1) is duplicated.
```
(The numbers may be different.)

**On SQLite:**
```
synapse.storage.background_updates - 623 - INFO - background_updates-0 - Adding index state_group_edges_unique_idx to state_group_edges
synapse.storage.background_updates - 282 - ERROR - background_updates-0 - Error doing update
...
sqlite3.IntegrityError: UNIQUE constraint failed: state_group_edges.state_group, state_group_edges.prev_state_group
```


<details>
<summary><b>Expand this section for steps to resolve this problem</b></summary>

### On Postgres

Connect to your database with `psql`.

```sql
BEGIN;
DELETE FROM state_group_edges WHERE (ctid, state_group, prev_state_group) IN (
  SELECT row_id, state_group, prev_state_group
  FROM (
    SELECT
      ctid AS row_id,
      MIN(ctid) OVER (PARTITION BY state_group, prev_state_group) AS min_row_id,
      state_group,
      prev_state_group
    FROM state_group_edges
  ) AS t1
  WHERE row_id <> min_row_id
);
COMMIT;
```


### On SQLite

At the command-line, use `sqlite3 path/to/your-homeserver-database.db`:

```sql
BEGIN;
DELETE FROM state_group_edges WHERE (rowid, state_group, prev_state_group) IN (
  SELECT row_id, state_group, prev_state_group
  FROM (
    SELECT
      rowid AS row_id,
      MIN(rowid) OVER (PARTITION BY state_group, prev_state_group) AS min_row_id,
      state_group,
      prev_state_group
    FROM state_group_edges
  )
  WHERE row_id <> min_row_id
);
COMMIT;
```


### For more details

[This comment on issue 11779](https://github.com/matrix-org/synapse/issues/11779#issuecomment-1131545970)
has queries that can be used to check a database for this problem in advance.

</details>

## New signature for the spam checker callback `check_event_for_spam`

The previous signature has been deprecated.

Whereas `check_event_for_spam` callbacks used to return `Union[str, bool]`, they should now return `Union["synapse.module_api.NOT_SPAM", "synapse.module_api.errors.Codes"]`.

This is part of an ongoing refactoring of the SpamChecker API to make it less ambiguous and more powerful.

If your module implements `check_event_for_spam` as follows:

```python
async def check_event_for_spam(event):
    if ...:
        # Event is spam
        return True
    # Event is not spam
    return False
```

you should rewrite it as follows:

```python
async def check_event_for_spam(event):
    if ...:
        # Event is spam, mark it as forbidden (you may use some more precise error
        # code if it is useful).
        return synapse.module_api.errors.Codes.FORBIDDEN
    # Event is not spam, mark it as such.
    return synapse.module_api.NOT_SPAM
```

# Upgrading to v1.59.0

## Device name lookup over federation has been disabled by default

The names of user devices are no longer visible to users on other homeservers by default.
Device IDs are unaffected, as these are necessary to facilitate end-to-end encryption.

To re-enable this functionality, set the
[`allow_device_name_lookup_over_federation`](https://matrix-org.github.io/synapse/v1.59/usage/configuration/config_documentation.html#federation)
homeserver config option to `true`.


## Deprecation of the `synapse.app.appservice` and `synapse.app.user_dir` worker application types

The `synapse.app.appservice` worker application type allowed you to configure a
single worker to use to notify application services of new events, as long
as this functionality was disabled on the main process with `notify_appservices: False`.
Further, the `synapse.app.user_dir` worker application type allowed you to configure
a single worker to be responsible for updating the user directory, as long as this
was disabled on the main process with `update_user_directory: False`.

To unify Synapse's worker types, the `synapse.app.appservice` worker application
type and the `notify_appservices` configuration option have been deprecated.
The `synapse.app.user_dir` worker application type and `update_user_directory`
configuration option have also been deprecated.

To get the same functionality as was provided by the deprecated options, it's now recommended that the `synapse.app.generic_worker`
worker application type is used and that the `notify_appservices_from_worker` and/or
`update_user_directory_from_worker` options are set to the name of a worker.

For the time being, the old options can be used alongside the new options to make
it easier to transition between the two configurations, however please note that:

- the options must not contradict each other (otherwise Synapse won't start); and
- the `notify_appservices` and `update_user_directory` options will be removed in a future release of Synapse.

Please see the [*Notifying Application Services*][v1_59_notify_ases_from] and
[*Updating the User Directory*][v1_59_update_user_dir] sections of the worker
documentation for more information.

[v1_59_notify_ases_from]: workers.md#notifying-application-services
[v1_59_update_user_dir]: workers.md#updating-the-user-directory


# Upgrading to v1.58.0

## Groups/communities feature has been disabled by default

The non-standard groups/communities feature in Synapse has been disabled by default
and will be removed in Synapse v1.61.0.


# Upgrading to v1.57.0

## Changes to database schema for application services

Synapse v1.57.0 includes a [change](https://github.com/matrix-org/synapse/pull/12209) to the
way transaction IDs are managed for application services. If your deployment uses a dedicated
worker for application service traffic, **it must be stopped** when the database is upgraded
(which normally happens when the main process is upgraded), to ensure the change is made safely
without any risk of reusing transaction IDs.

Deployments which do not use separate worker processes can be upgraded as normal. Similarly,
deployments where no application services are in use can be upgraded as normal.

<details>
<summary><b>Recovering from an incorrect upgrade</b></summary>

If the database schema is upgraded *without* stopping the worker responsible
for AS traffic, then the following error may be given when attempting to start
a Synapse worker or master process:

```
**********************************************************************************
 Error during initialisation:

 Postgres sequence 'application_services_txn_id_seq' is inconsistent with associated
 table 'application_services_txns'. This can happen if Synapse has been downgraded and
 then upgraded again, or due to a bad migration.

 To fix this error, shut down Synapse (including any and all workers)
 and run the following SQL:

     SELECT setval('application_services_txn_id_seq', (
         SELECT GREATEST(MAX(txn_id), 0) FROM application_services_txns
     ));

 See docs/postgres.md for more information.

 There may be more information in the logs.
**********************************************************************************
```

This error may also be seen if Synapse is *downgraded* to an earlier version,
and then upgraded again to v1.57.0 or later.

In either case:

 1. Ensure that the worker responsible for AS traffic is stopped.
 2. Run the SQL command given in the error message via `psql`.

Synapse should then start correctly.
</details>

# Upgrading to v1.56.0

## Open registration without verification is now disabled by default

Synapse will refuse to start if registration is enabled without email, captcha, or token-based verification unless the new config
flag `enable_registration_without_verification` is set to "true".

## Groups/communities feature has been deprecated

The non-standard groups/communities feature in Synapse has been deprecated and will
be disabled by default in Synapse v1.58.0.

You can test disabling it by adding the following to your homeserver configuration:

```yaml
experimental_features:
  groups_enabled: false
```

## Change in behaviour for PostgreSQL databases with unsafe locale

Synapse now refuses to start when using PostgreSQL with non-`C` values for `COLLATE` and
`CTYPE` unless the config flag `allow_unsafe_locale`, found in the database section of
the configuration file, is set to `true`. See the [PostgreSQL documentation](https://matrix-org.github.io/synapse/latest/postgres.html#fixing-incorrect-collate-or-ctype)
for more information and instructions on how to fix a database with incorrect values.

# Upgrading to v1.55.0

## `synctl` script has been moved

The `synctl` script
[has been made](https://github.com/matrix-org/synapse/pull/12140) an
[entry point](https://packaging.python.org/en/latest/specifications/entry-points/)
and no longer exists at the root of Synapse's source tree. If you wish to use
`synctl` to manage your homeserver, you should invoke `synctl` directly, e.g.
`synctl start` instead of `./synctl start` or `/path/to/synctl start`.

You will need to ensure `synctl` is on your `PATH`.
  - This is automatically the case when using
    [Debian packages](https://packages.matrix.org/debian/) or
    [docker images](https://hub.docker.com/r/matrixdotorg/synapse)
    provided by Matrix.org.
  - When installing from a wheel, sdist, or PyPI, a `synctl` executable is added
    to your Python installation's `bin`. This should be on your `PATH`
    automatically, though you might need to activate a virtual environment
    depending on how you installed Synapse.


## Compatibility dropped for Mjolnir 1.3.1 and earlier

Synapse v1.55.0 drops support for Mjolnir 1.3.1 and earlier.
If you use the Mjolnir module to moderate your homeserver,
please upgrade Mjolnir to version 1.3.2 or later before upgrading Synapse.


# Upgrading to v1.54.0

## Legacy structured logging configuration removal

This release removes support for the `structured: true` logging configuration
which was deprecated in Synapse v1.23.0. If your logging configuration contains
`structured: true` then it should be modified based on the