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Remove support for MSC3852: Expose user agent information on Device as the MSC was closed. - #19430

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Remove support for MSC3852: Expose user agent information on Device as the MSC was closed.#19430
reivilibre merged 2 commits into
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Fixes: #14836

Discovered whilst looking at the state of MSCs in Synapse.

Signed-off-by: Olivier 'reivilibre <oliverw@matrix.org>
@reivilibre reivilibre changed the title Remove support for [MSC3852: Expose user agent information on Device](https://github.com/matrix-org/matrix-spec-proposals/pull/3852) as the MSC was closed. Remove support for MSC3852: Expose user agent information on Device as the MSC was closed. Feb 3, 2026
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reivilibre marked this pull request as ready for review March 3, 2026 17:43
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reivilibre requested a review from a team as a code owner March 3, 2026 17:43
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Comment thread changelog.d/19430.removal
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Remove support for [MSC3852: Expose user agent information on Device](https://github.com/matrix-org/matrix-spec-proposals/pull/3852) as the MSC was closed. No newline at end of file

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This endpoint is still in use by the current implementation of the Device Manager in Element clients, so I feel we should support it for a little bit longer until that implementation is rewritten to no longer use this endpoint, and some time further after that still. But we should eventually remove it.

No wider deprecation period is necessary as this is an experimental feature. But it would be nice to coordinate with the Element devs before doing so as not to pull the rug out from under them.

-- #14836

Feels like this doesn't matter as it's been 3+ years since that was written but just for completeness sake, were Element clients transitioned away already?

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It appears they still reference MSC3852 in the code https://github.com/search?q=repo%3Aelement-hq%2Felement-web%20MSC3852&type=code

However, they must also function without it, as other homeserver implementations won't provide this endpoint. So it's not a blocker for us removing support for a rejected MSC.

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@reivilibre any reason you haven't merged this?

@reivilibre
reivilibre merged commit 0d4accb into develop Mar 17, 2026
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reivilibre deleted the rei/rm_msc3852 branch March 17, 2026 17:08
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@reivilibre any reason you haven't merged this?

Only by forgetting I opened it

FrenchGithubUser pushed a commit to famedly/synapse-upstreaming that referenced this pull request Jun 12, 2026
…s the MSC was closed. (element-hq#19430)

Fixes: element-hq#14836

Discovered whilst looking at the state of MSCs in Synapse.

---------

Signed-off-by: Olivier 'reivilibre <oliverw@matrix.org>
netbsd-srcmastr pushed a commit to NetBSD/pkgsrc that referenced this pull request Jul 7, 2026
Tested on NetBSD 10 amd64 with 2026Q2 environment.

# Synapse 1.156.0 (2026-07-07)

## Features

- Expose [MSC4354 Sticky Events](matrix-org/matrix-spec-proposals#4354) over [MSC4186 (Simplified) Sliding Sync](matrix-org/matrix-spec-proposals#4186). ([\#19591](element-hq/synapse#19591))
- Stabilize support for sending ephemeral events to application services, as per [MSC2409](matrix-org/matrix-spec-proposals#2409). Contributed by @jason-famedly @ Famedly. ([\#19758](element-hq/synapse#19758))
- Include `allowed_room_ids` in the `/summary` client-server API response for rooms with restricted join rules, as required by Matrix 1.15.
  Contributed by @FrenchGithubUser @famedly. ([\#19762](element-hq/synapse#19762))
- [MSC4140: Cancellable delayed events](matrix-org/matrix-spec-proposals#4140): Allow authentication on delayed event management endpoints (such as `/restart`) to bypass ratelimits for unauthenticated requests based on the client IP address. ([\#19794](element-hq/synapse#19794))
- Add new metric `synapse_non_deactivated_user_count` which tracks the number of non-deactivated users in the database, split by `app_service`. ([\#19848](element-hq/synapse#19848))
- The `GET /_matrix/client/unstable/org.matrix.msc1763/retention/configuration` endpoint is now provided when retention
  is enabled and `experimental_features.msc1763_enabled` is enabled, based on
  [MSC1763](matrix-org/matrix-spec-proposals#1763). ([\#19853](element-hq/synapse#19853))
- Add experimental support for [MSC4491: Invite reasons in room creation](matrix-org/matrix-spec-proposals#4491). ([\#19874](element-hq/synapse#19874))


# Synapse 1.155.0 (2026-06-16)


# Synapse 1.154.0 (2026-06-04)

## Features

- Add support for [MSC4452: Preview URL capabilities API](matrix-org/matrix-spec-proposals#4452) which exposes a `io.element.msc4452.preview_url` capability.
  If `experimental_features.msc4452_enabled` is `true`, the `/_matrix/(client/v1/media|media/v3)/preview_url` endpoint
  now responds with a 403 status code when the capability is disabled. ([\#19715](element-hq/synapse#19715))


# Synapse 1.153.0 (2026-05-19)

## Features

- Make ACLs apply to EDUs per [MSC4163](matrix-org/matrix-spec-proposals#4163). ([\#18475](element-hq/synapse#18475))
- Stabilize [MSC3266: Room summary API](matrix-org/matrix-spec-proposals#3266), removing the experimental config flag `msc3266_enabled`. Contributed by @dasha-uwu. ([\#19720](element-hq/synapse#19720))
- Partial [MSC4311](matrix-org/matrix-spec-proposals#4311) implementation: `m.room.create` is now a required part of stripped `invite_state`/`knock_state` . Contributed by @FrenchGithubUser @famedly. ([\#19722](element-hq/synapse#19722))
- Expose `tombstoned` and `replacement_room` in room details on admin API endpoint `GET /_synapse/admin/v1/rooms/<room_id>`. Contributed by Noah Markert. ([\#19737](element-hq/synapse#19737))


# Synapse 1.152.1 (2026-05-07)


# Synapse 1.152.0 (2026-04-28)

## Features

- Add a ["Listing quarantined media changes" Admin API](https://element-hq.github.io/synapse/latest/admin_api/media_admin_api.html#listing-quarantined-media-changes) for retrieving a paginated record of when media became (un)quarantined. ([\#19558](element-hq/synapse#19558), [\#19677](element-hq/synapse#19677), [\#19694](element-hq/synapse#19694))
- Advertise [MSC4445](matrix-org/matrix-spec-proposals#4445) sync timeline order in `unstable_features`. ([\#19642](element-hq/synapse#19642))
- Report the Rust compiler version used in the Prometheus metrics. Contributed by Noah Markert. ([\#19643](element-hq/synapse#19643))
- Passthrough 'article' and 'profile' OpenGraph metadata on URL preview requests. ([\#19659](element-hq/synapse#19659))
- Add a way to re-sign local events with a new signing key. ([\#19668](element-hq/synapse#19668))
- Support [MSC4450: Identity Provider selection for User-Interactive Authentication with Legacy Single Sign-On](matrix-org/matrix-spec-proposals#4450). ([\#19693](element-hq/synapse#19693))
- Add experimental support for [MSC4242](matrix-org/matrix-spec-proposals#4242): State DAGs. Excludes federation support. ([\#19424](element-hq/synapse#19424))
- Adds [Admin API](https://element-hq.github.io/synapse/latest/usage/administration/admin_api/index.html) endpoints to
  list, fetch and delete user reports. ([\#19657](element-hq/synapse#19657))
- Reduce database disk space usage by pruning old rows from `device_lists_changes_in_room`. ([\#19473](element-hq/synapse#19473), [\#19709](element-hq/synapse#19709))


# Synapse 1.151.0 (2026-04-07)

## Features

- Add stable support for [MSC4284](matrix-org/matrix-spec-proposals#4284) Policy Servers. ([\#19503](element-hq/synapse#19503))
- Update and stabilize support for [MSC2666](matrix-org/matrix-spec-proposals#2666): Get rooms in common with another user. Contributed by @tulir @ Beeper. ([\#19511](element-hq/synapse#19511))
- Updated experimental support for [MSC4388: Secure out-of-band channel for sign in with QR](matrix-org/matrix-spec-proposals#4388). ([\#19573](element-hq/synapse#19573))
- Stabilize `room_version` and `encryption` fields in the space/room `/hierarchy` API (part of [MSC3266](matrix-org/matrix-spec-proposals#3266)). ([\#19576](element-hq/synapse#19576))
- Introduce a [configuration option](https://element-hq.github.io/synapse/latest/usage/configuration/config_documentation.html#matrix_authentication_service) to allow using HTTP/2 over plaintext when Synapse connects to Matrix Authentication Service. ([\#19586](element-hq/synapse#19586))

## Deprecations and Removals

- Remove support for [MSC3852: Expose user agent information on Device](matrix-org/matrix-spec-proposals#3852) as the MSC was closed. ([\#19430](element-hq/synapse#19430))


# Synapse 1.150.0 (2026-03-24)

## Features

- Add experimental support for the [MSC4370](matrix-org/matrix-spec-proposals#4370) Federation API `GET /extremities` endpoint. ([\#19314](element-hq/synapse#19314))
- [MSC4140: Cancellable delayed events](matrix-org/matrix-spec-proposals#4140): When persisting a delayed event to the timeline, include its `delay_id` in the event's `unsigned` section in `/sync` responses to the event sender. ([\#19479](element-hq/synapse#19479))
- Expose [MSC4354 Sticky Events](matrix-org/matrix-spec-proposals#4354) over the legacy (v3) /sync API. ([\#19487](element-hq/synapse#19487))
- When Matrix Authentication Service (MAS) integration is enabled, allow MAS to set the user locked status in Synapse. ([\#19554](element-hq/synapse#19554))
pull Bot pushed a commit to Kab1r/element-web that referenced this pull request Jul 23, 2026
* Remove support for MSC3391 & MSC3852

As they were both rejected & closed.

Synapse already removed support for MSC3852 which means it already did nothing: element-hq/synapse#19430

* Update snapshot
pull Bot pushed a commit to esinanturan/matrix-js-sdk that referenced this pull request Jul 23, 2026
* Remove support for MSC3391 & MSC3852

As they were both rejected & closed.

Synapse already removed support for MSC3852 which means it already did nothing: element-hq/synapse#19430

* Update test

* Update src/client.ts
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We should remove experimental support for MSC3852 as it has now closed

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