Bump github.com/docker/docker

Bumps [github.com/docker/docker](https://github.com/docker/docker) from 26.1.5+incompatible to 28.3.3+incompatible.
- [Release notes](https://github.com/docker/docker/releases)
- [Commits](https://github.com/docker/docker/compare/v26.1.5...v28.3.3)

---
updated-dependencies:
- dependency-name: github.com/docker/docker
  dependency-version: 28.3.3+incompatible
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

CHANGES.md

@@ -1,5 +1,34 @@
 # Changelog
 
+## Dendrite 0.15.1 (2025-08-13)
+
+### Bug fixes
+ - Fixed an issue which could cause Dendrite to become unresponsive for minutes at a time. (contributed by [viviicat](https://github.com/viviicat))
+ - Fixed an issue which prevented joining v12 rooms in some circumstances.
+ - Fixed an issue which prevented sending invites to v12 rooms.
+ - Fixed an issue which prevented some clients from syncing v12 rooms.
+ - Fixed an issue where a single badly formed PDU would block entire transactions of PDUs being processed. See https://github.com/element-hq/synapse/issues/7543 for the related issue on Synapse.
+
+## Dendrite 0.15.0 (2025-08-12)
+
+### ⚠ Important
+
+This is a security release, adding support for [room version 12](https://matrix.org/blog/2025/08/security-release/).
+
+### Features
+ - Add support for [MSC4163](https://github.com/matrix-org/matrix-spec-proposals/pull/4163).
+ - Add support for [MSC3967](https://github.com/matrix-org/matrix-spec-proposals/pull/3967).
+ - Add support for room version 12.
+
+### Bug fixes
+ - Refactored NATS JetStream code to gracefully handle more potential errors. (contributed by [neilalexander](https://github.com/neilalexander))
+ - Refactored NATS startup and readiness checking. (contributed by [neilalexander](https://github.com/neilalexander))
+ - Updated NATS to 2.11.7. (contributed by [neilalexander](https://github.com/neilalexander))
+ - Fixed an issue which could cause Dendrite to become unresponsive for minutes at a time. (contributed by [viviicat](https://github.com/viviicat))
+ - Order events when backfilling to reduce the amount of unecessary `/state_ids` requests.
+ - Gracefully handle incorrect sync filter JSON.
+ - Fixed an issue which prevented device deletion working correctly. (contributed by [robinsdan](https://github.com/robinsdan))
+
 ## Dendrite 0.14.1 (2025-01-16)
 
 ### ⚠ Important

README.md

@@ -2,14 +2,14 @@
 
 [![Build status](https://github.com/element-hq/dendrite/actions/workflows/dendrite.yml/badge.svg?event=push)](https://github.com/element-hq/dendrite/actions/workflows/dendrite.yml) [![Dendrite](https://img.shields.io/matrix/dendrite:matrix.org.svg?label=%23dendrite%3Amatrix.org&logo=matrix&server_fqdn=matrix.org)](https://matrix.to/#/#dendrite:matrix.org) [![Dendrite Dev](https://img.shields.io/matrix/dendrite-dev:matrix.org.svg?label=%23dendrite-dev%3Amatrix.org&logo=matrix&server_fqdn=matrix.org)](https://matrix.to/#/#dendrite-dev:matrix.org)
 
-Dendrite is a second-generation Matrix homeserver written in Go.
-It intends to provide an **efficient**, **reliable** and **scalable** alternative to [Synapse](https://github.com/matrix-org/synapse):
+Dendrite is a second-generation Matrix homeserver written in Go. It is currently in maintenance mode,
+meaning only security fixes are being applied, for example [room version 12](https://matrix.org/blog/2025/08/security-release/).
+
+It intends to provide an **efficient** and **reliable** alternative to [Synapse](https://github.com/matrix-org/synapse):
 
 - Efficient: A small memory footprint with better baseline performance than an out-of-the-box Synapse.
 - Reliable: Implements the Matrix specification as written, using the
-  [same test suite](https://github.com/matrix-org/sytest) as Synapse as well as
-  a [brand new Go test suite](https://github.com/matrix-org/complement).
-- Scalable: can run on multiple machines and eventually scale to massive homeserver deployments.
+  [same](https://github.com/matrix-org/sytest) test [suites](https://github.com/matrix-org/complement) as Synapse.
 
 Dendrite is **beta** software, which means:
 
@@ -31,6 +31,10 @@ If you have further questions, please take a look at [our FAQ](docs/FAQ.md) or j
 - **[#dendrite-dev:matrix.org](https://matrix.to/#/#dendrite-dev:matrix.org)** - The place for developers, where all Dendrite development discussion happens
 - **[#dendrite-alerts:matrix.org](https://matrix.to/#/#dendrite-alerts:matrix.org)** - Release notifications and important info, highly recommended for all Dendrite server admins
 
+Dendrite does not currently support the following MSCs, which impacts the ability to use Element X with Dendrite servers:
+ - [MSC4186](https://github.com/matrix-org/matrix-spec-proposals/pull/4186): Simplified Sliding Sync
+ - [MSC3861](https://github.com/matrix-org/matrix-spec-proposals/pull/3861): Next-gen auth OIDC
+
 ## Requirements
 
 See the [Planning your Installation](https://element-hq.github.io/dendrite/installation/planning) page for
@@ -83,36 +87,6 @@ $ ./bin/create-account --config dendrite.yaml --username alice
 
 Then point your favourite Matrix client at `http://localhost:8008` or `https://localhost:8448`.
 
-## Progress
-
-We use a script called "Are We Synapse Yet" which checks Sytest compliance rates. Sytest is a black-box homeserver
-test rig with around 900 tests. The script works out how many of these tests are passing on Dendrite and it
-updates with CI. As of January 2023, we have 100% server-server parity with Synapse, and the client-server parity is at 93% , though check
-CI for the latest numbers. In practice, this means you can communicate locally and via federation with Synapse
-servers such as matrix.org reasonably well, although there are still some missing features (like SSO and Third-party ID APIs).
-
-We are prioritising features that will benefit single-user homeservers first (e.g Receipts, E2E) rather
-than features that massive deployments may be interested in (OpenID, Guests, Admin APIs, AS API).
-This means Dendrite supports amongst others:
-
-- Core room functionality (creating rooms, invites, auth rules)
-- Room versions 1 to 10 supported
-- Backfilling locally and via federation
-- Accounts, profiles and devices
-- Published room lists
-- Typing
-- Media APIs
-- Redaction
-- Tagging
-- Context
-- E2E keys and device lists
-- Receipts
-- Push
-- Guests
-- User Directory
-- Presence
-- Fulltext search
-
 ## Contributing
 
 We would be grateful for any help on issues marked as

go.mod

@@ -10,7 +10,7 @@ require (
 	github.com/coder/websocket v1.8.13
 	github.com/cretz/bine v0.2.0
 	github.com/dgraph-io/ristretto v0.2.0
-	github.com/docker/docker v26.1.5+incompatible
+	github.com/docker/docker v28.3.3+incompatible
 	github.com/docker/go-connections v0.5.0
 	github.com/eyedeekay/goSam v0.32.54
 	github.com/eyedeekay/onramp v0.33.8
@@ -25,7 +25,7 @@ require (
 	github.com/matrix-org/dugong v0.0.0-20210921133753-66e6b1c67e2e
 	github.com/matrix-org/go-sqlite3-js v0.0.0-20220419092513-28aa791a1c91
 	github.com/matrix-org/gomatrix v0.0.0-20220926102614-ceba4d9f7530
-	github.com/matrix-org/gomatrixserverlib v0.0.0-20250811193806-b7e0e0824751
+	github.com/matrix-org/gomatrixserverlib v0.0.0-20250813150445-9f5070a65744
 	github.com/matrix-org/pinecone v0.11.1-0.20230810010612-ea4c33717fd7
 	github.com/matrix-org/util v0.0.0-20221111132719-399730281e66
 	github.com/mattn/go-sqlite3 v1.14.28
@@ -83,6 +83,8 @@ require (
 	github.com/blevesearch/zapx/v15 v15.4.2 // indirect
 	github.com/blevesearch/zapx/v16 v16.2.4 // indirect
 	github.com/cespare/xxhash/v2 v2.3.0 // indirect
+	github.com/containerd/errdefs v1.0.0 // indirect
+	github.com/containerd/errdefs/pkg v0.3.0 // indirect
 	github.com/containerd/log v0.1.0 // indirect
 	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/distribution/reference v0.6.0 // indirect
@@ -109,6 +111,7 @@ require (
 	github.com/mattn/go-isatty v0.0.20 // indirect
 	github.com/minio/highwayhash v1.0.3 // indirect
 	github.com/moby/docker-image-spec v1.3.1 // indirect
+	github.com/moby/sys/atomicwriter v0.1.0 // indirect
 	github.com/moby/term v0.5.0 // indirect
 	github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd // indirect
 	github.com/modern-go/reflect2 v1.0.2 // indirect

go.sum

@@ -73,6 +73,10 @@ github.com/codeclysm/extract v2.2.0+incompatible h1:q3wyckoA30bhUSiwdQezMqVhwd8+
 github.com/codeclysm/extract v2.2.0+incompatible/go.mod h1:2nhFMPHiU9At61hz+12bfrlpXSUrOnK+wR+KlGO4Uks=
 github.com/coder/websocket v1.8.13 h1:f3QZdXy7uGVz+4uCJy2nTZyM0yTBj8yANEHhqlXZ9FE=
 github.com/coder/websocket v1.8.13/go.mod h1:LNVeNrXQZfe5qhS9ALED3uA+l5pPqvwXg3CKoDBB2gs=
+github.com/containerd/errdefs v1.0.0 h1:tg5yIfIlQIrxYtu9ajqY42W3lpS19XqdxRQeEwYG8PI=
+github.com/containerd/errdefs v1.0.0/go.mod h1:+YBYIdtsnF4Iw6nWZhJcqGSg/dwvV7tyJ/kCkyJ2k+M=
+github.com/containerd/errdefs/pkg v0.3.0 h1:9IKJ06FvyNlexW690DXuQNx2KA2cUJXx151Xdx3ZPPE=
+github.com/containerd/errdefs/pkg v0.3.0/go.mod h1:NJw6s9HwNuRhnjJhM7pylWwMyAkmCQvQ4GpJHEqRLVk=
 github.com/containerd/log v0.1.0 h1:TCJt7ioM2cr/tfR8GPbGf9/VRAX8D2B4PjzCpfX540I=
 github.com/containerd/log v0.1.0/go.mod h1:VRRf09a7mHDIRezVKTRCrOq78v577GXq3bSa3EhrzVo=
 github.com/coreos/go-systemd/v22 v22.5.0/go.mod h1:Y58oyj3AT4RCenI/lSvhwexgC+NSVTIJ3seZv2GcEnc=
@@ -88,8 +92,8 @@ github.com/dgryski/go-farm v0.0.0-20200201041132-a6ae2369ad13 h1:fAjc9m62+UWV/WA
 github.com/dgryski/go-farm v0.0.0-20200201041132-a6ae2369ad13/go.mod h1:SqUrOPUnsFjfmXRMNPybcSiG0BgUW2AuFH8PAnS2iTw=
 github.com/distribution/reference v0.6.0 h1:0IXCQ5g4/QMHHkarYzh5l+u8T3t73zM5QvfrDyIgxBk=
 github.com/distribution/reference v0.6.0/go.mod h1:BbU0aIcezP1/5jX/8MP0YiH4SdvB5Y4f/wlDRiLyi3E=
-github.com/docker/docker v26.1.5+incompatible h1:NEAxTwEjxV6VbBMBoGG3zPqbiJosIApZjxlbrG9q3/g=
-github.com/docker/docker v26.1.5+incompatible/go.mod h1:eEKB0N0r5NX/I1kEveEz05bcu8tLC/8azJZsviup8Sk=
+github.com/docker/docker v28.3.3+incompatible h1:Dypm25kh4rmk49v1eiVbsAtpAsYURjYkaKubwuBdxEI=
+github.com/docker/docker v28.3.3+incompatible/go.mod h1:eEKB0N0r5NX/I1kEveEz05bcu8tLC/8azJZsviup8Sk=
 github.com/docker/go-connections v0.5.0 h1:USnMq7hx7gwdVZq1L49hLXaFtUdTADjXGp+uj1Br63c=
 github.com/docker/go-connections v0.5.0/go.mod h1:ov60Kzw0kKElRwhNs9UlUHAE/F9Fe6GLaXnqyDdmEXc=
 github.com/docker/go-units v0.5.0 h1:69rxXcBk27SvSaaxTtLh/8llcHD8vYHT7WSdRZ/jvr4=
@@ -237,8 +241,8 @@ github.com/matrix-org/go-sqlite3-js v0.0.0-20220419092513-28aa791a1c91 h1:s7fexw
 github.com/matrix-org/go-sqlite3-js v0.0.0-20220419092513-28aa791a1c91/go.mod h1:e+cg2q7C7yE5QnAXgzo512tgFh1RbQLC0+jozuegKgo=
 github.com/matrix-org/gomatrix v0.0.0-20220926102614-ceba4d9f7530 h1:kHKxCOLcHH8r4Fzarl4+Y3K5hjothkVW5z7T1dUM11U=
 github.com/matrix-org/gomatrix v0.0.0-20220926102614-ceba4d9f7530/go.mod h1:/gBX06Kw0exX1HrwmoBibFA98yBk/jxKpGVeyQbff+s=
-github.com/matrix-org/gomatrixserverlib v0.0.0-20250811193806-b7e0e0824751 h1:x1pC7Nt1Qb24q9WtPybMHWo2uVFTzCKtlUAzarju8bk=
-github.com/matrix-org/gomatrixserverlib v0.0.0-20250811193806-b7e0e0824751/go.mod h1:b6KVfDjXjA5Q7vhpOaMqIhFYvu5BuFVZixlNeTV/CLc=
+github.com/matrix-org/gomatrixserverlib v0.0.0-20250813150445-9f5070a65744 h1:5GvC2FD9O/PhuyY95iJQdNYHbDioEhMWdeMP9maDUL8=
+github.com/matrix-org/gomatrixserverlib v0.0.0-20250813150445-9f5070a65744/go.mod h1:b6KVfDjXjA5Q7vhpOaMqIhFYvu5BuFVZixlNeTV/CLc=
 github.com/matrix-org/pinecone v0.11.1-0.20230810010612-ea4c33717fd7 h1:6t8kJr8i1/1I5nNttw6nn1ryQJgzVlBmSGgPiiaTdw4=
 github.com/matrix-org/pinecone v0.11.1-0.20230810010612-ea4c33717fd7/go.mod h1:ReWMS/LoVnOiRAdq9sNUC2NZnd1mZkMNB52QhpTRWjg=
 github.com/matrix-org/util v0.0.0-20221111132719-399730281e66 h1:6z4KxomXSIGWqhHcfzExgkH3Z3UkIXry4ibJS4Aqz2Y=
@@ -259,6 +263,10 @@ github.com/minio/highwayhash v1.0.3 h1:kbnuUMoHYyVl7szWjSxJnxw11k2U709jqFPPmIUyD
 github.com/minio/highwayhash v1.0.3/go.mod h1:GGYsuwP/fPD6Y9hMiXuapVvlIUEhFhMTh0rxU3ik1LQ=
 github.com/moby/docker-image-spec v1.3.1 h1:jMKff3w6PgbfSa69GfNg+zN/XLhfXJGnEx3Nl2EsFP0=
 github.com/moby/docker-image-spec v1.3.1/go.mod h1:eKmb5VW8vQEh/BAr2yvVNvuiJuY6UIocYsFu/DxxRpo=
+github.com/moby/sys/atomicwriter v0.1.0 h1:kw5D/EqkBwsBFi0ss9v1VG3wIkVhzGvLklJ+w3A14Sw=
+github.com/moby/sys/atomicwriter v0.1.0/go.mod h1:Ul8oqv2ZMNHOceF643P6FKPXeCmYtlQMvpizfsSoaWs=
+github.com/moby/sys/sequential v0.6.0 h1:qrx7XFUd/5DxtqcoH1h438hF5TmOvzC/lspjy7zgvCU=
+github.com/moby/sys/sequential v0.6.0/go.mod h1:uyv8EUTrca5PnDsdMGXhZe6CCe8U/UiTWd+lL+7b/Ko=
 github.com/moby/term v0.5.0 h1:xt8Q1nalod/v7BqbG21f8mQPqH+xAaC9C3N3wfWbVP0=
 github.com/moby/term v0.5.0/go.mod h1:8FzsFHVUBGZdbDsJw/ot+X+d5HLUbvklYLJ9uGfcI3Y=
 github.com/modern-go/concurrent v0.0.0-20180228061459-e0a39a4cb421/go.mod h1:6dJC0mAP4ikYIbvyc7fijjWJddQyLn8Ig3JB5CqoB9Q=

internal/transactionrequest.go

@@ -134,6 +134,8 @@ func (t *TxnReq) ProcessTransaction(ctx context.Context) (*fclient.RespSend, *ut
 		}
 		event, err := verImpl.NewEventFromUntrustedJSON(pdu)
 		if err != nil {
+			/* Do not reject the entire transaction for a single bad PDU, that's dumb.
+
 			if _, ok := err.(gomatrixserverlib.BadJSONError); ok {
 				// Room version 6 states that homeservers should strictly enforce canonical JSON
 				// on PDUs.
@@ -146,7 +148,7 @@ func (t *TxnReq) ProcessTransaction(ctx context.Context) (*fclient.RespSend, *ut
 					Code: 400,
 					JSON: spec.BadJSON("PDU contains bad JSON"),
 				}
-			}
+			} */
 			util.GetLogger(ctx).WithError(err).Debugf("Transaction: Failed to parse event JSON of event %s", string(pdu))
 			continue
 		}

internal/version.go

@@ -17,7 +17,7 @@ var build string
 
 const (
 	VersionMajor = 0
-	VersionMinor = 14
+	VersionMinor = 15
 	VersionPatch = 1
 	VersionTag   = "" // example: "rc1"
 

roomserver/internal/input/input.go

@@ -101,9 +101,12 @@ type worker struct {
 	roomID       string
 	subscription *nats.Subscription
 	sentryHub    *sentry.Hub
+	ephemeralSeq uint64
+	// last seq we fully processed
+	durableSeq uint64
 }
 
-func (r *Inputer) startWorkerForRoom(roomID string) {
+func (r *Inputer) startWorkerForRoom(roomID string, seq uint64) {
 	v, loaded := r.workers.LoadOrStore(roomID, &worker{
 		r:         r,
 		roomID:    roomID,
@@ -112,6 +115,9 @@ func (r *Inputer) startWorkerForRoom(roomID string) {
 	w := v.(*worker)
 	w.Lock()
 	defer w.Unlock()
+
+	w.ephemeralSeq = seq
+
 	if !loaded || w.subscription == nil {
 		streamName := r.Cfg.Matrix.JetStream.Prefixed(jetstream.InputRoomEvent)
 		consumer := r.Cfg.Matrix.JetStream.Prefixed("RoomInput" + jetstream.Tokenise(w.roomID))
@@ -226,7 +232,8 @@ func (r *Inputer) Start() error {
 		"", // This is blank because we specified it in BindStream.
 		func(m *nats.Msg) {
 			roomID := m.Header.Get(jetstream.RoomID)
-			r.startWorkerForRoom(roomID)
+			meta, _ := m.Metadata()
+			r.startWorkerForRoom(roomID, meta.Sequence.Stream)
 			_ = m.Ack()
 		},
 		nats.HeadersOnly(),
@@ -264,7 +271,7 @@ func (w *worker) _next() {
 	})
 	msgs, err := w.subscription.Fetch(1, nats.Context(ctx))
 	switch err {
-	case nil, nats.ErrTimeout, context.DeadlineExceeded, context.Canceled:
+	case nil:
 		// Is the server shutting down? If so, stop processing.
 		if w.r.ProcessContext.Context().Err() != nil {
 			return
@@ -272,14 +279,33 @@ func (w *worker) _next() {
 		// Make sure that once we're done here, we queue up another call
 		// to _next in the inbox.
 		defer w.Act(nil, w._next)
-
-		// If no error was reported, but we didn't get exactly one message,
-		// then skip over this and try again on the next iteration.
-		if len(msgs) != 1 {
+	case nats.ErrTimeout, context.DeadlineExceeded, context.Canceled:
+		// Is the server shutting down? If so, stop processing.
+		if w.r.ProcessContext.Context().Err() != nil {
+			return
+		}
+		// The context exceeded, so we've been waiting for more than a
+		// minute for activity in this room. At this point we will shut
+		// down the subscriber to free up resources. It'll get started
+		// again if new activity happens.
+		w.Lock()
+		// inside the lock, let's check if the ephemeral consumer saw something new!
+		// If so, we do have new messages after all, they just came at a bad time.
+		if w.ephemeralSeq > w.durableSeq {
+			w.Unlock()
+			w.Act(nil, w._next)
 			return
 		}
 
+		if err = w.subscription.Unsubscribe(); err != nil {
+			logrus.WithError(err).Errorf("Failed to unsubscribe to stream for room %q", w.roomID)
+		}
+		w.subscription = nil
+		w.Unlock()
+		return
 	case nats.ErrConsumerDeleted, nats.ErrConsumerNotFound:
+		w.Lock()
+		defer w.Unlock()
 		// The consumer is gone, therefore it's reached the inactivity
 		// threshold. Clean up and stop processing at this point, if a
 		// new event comes in for this room then the ordered consumer
@@ -287,21 +313,20 @@ func (w *worker) _next() {
 		if err = w.subscription.Unsubscribe(); err != nil {
 			logrus.WithError(err).Errorf("Failed to unsubscribe to stream for room %q", w.roomID)
 		}
-		w.Lock()
 		w.subscription = nil
-		w.Unlock()
 		return
-
 	default:
 		// Something went wrong while trying to fetch the next event
 		// from the queue. In which case, we'll shut down the subscriber
 		// and wait to be notified about new room activity again. Maybe
 		// the problem will be corrected by then.
+		// atomically clear the subscription and unsubscribe
+		w.Lock()
+
 		logrus.WithError(err).Errorf("Failed to get next stream message for room %q", w.roomID)
 		if err = w.subscription.Unsubscribe(); err != nil {
 			logrus.WithError(err).Errorf("Failed to unsubscribe to stream for room %q", w.roomID)
 		}
-		w.Lock()
 		w.subscription = nil
 		w.Unlock()
 		return
@@ -310,10 +335,19 @@ func (w *worker) _next() {
 	// Since we either Ack() or Term() the message at this point, we can defer decrementing the room backpressure
 	defer roomserverInputBackpressure.With(prometheus.Labels{"room_id": w.roomID}).Dec()
 
+	// If no error was reported, but we didn't get exactly one message,
+	// then skip over this and try again on the next iteration.
+	if len(msgs) != 1 {
+		return
+	}
+
 	// Try to unmarshal the input room event. If the JSON unmarshalling
 	// fails then we'll terminate the message — this notifies NATS that
 	// we are done with the message and never want to see it again.
 	msg := msgs[0]
+	meta, _ := msg.Metadata()
+	w.durableSeq = meta.Sequence.Stream
+
 	var inputRoomEvent api.InputRoomEvent
 	if err = json.Unmarshal(msg.Data, &inputRoomEvent); err != nil {
 		// using AckWait here makes the call synchronous; 5 seconds is the default value used by NATS

roomserver/internal/perform/perform_invite.go

@@ -31,7 +31,11 @@ type QueryState struct {
 }
 
 func (q *QueryState) GetAuthEvents(ctx context.Context, event gomatrixserverlib.PDU) (gomatrixserverlib.AuthEventProvider, error) {
-	return helpers.GetAuthEvents(ctx, q.Database, event.Version(), event, event.AuthEventIDs())
+	authEventIDs := event.AuthEventIDs()
+	if gomatrixserverlib.MustGetRoomVersion(event.Version()).DomainlessRoomIDs() {
+		authEventIDs = append(authEventIDs, "$"+event.RoomID().String()[1:])
+	}
+	return helpers.GetAuthEvents(ctx, q.Database, event.Version(), event, authEventIDs)
 }
 
 func (q *QueryState) GetState(ctx context.Context, roomID spec.RoomID, stateWanted []gomatrixserverlib.StateKeyTuple) ([]gomatrixserverlib.PDU, error) {

syncapi/streams/stream_pdu.go

@@ -404,7 +404,9 @@ func (p *PDUStreamProvider) addRoomDeltaToResponse(
 	// "state" section and kept in "timeline".
 	sEvents := gomatrixserverlib.HeaderedReverseTopologicalOrdering(
 		gomatrixserverlib.ToPDUs(removeDuplicates(delta.StateEvents, events)),
-		gomatrixserverlib.TopologicalOrderByAuthEvents,
+		// sorting by auth events is not stable unless we know the create and historical PL events,
+		// which we don't for deltas like this.
+		gomatrixserverlib.TopologicalOrderByPrevEvents,
 	)
 	delta.StateEvents = make([]*rstypes.HeaderedEvent, len(sEvents))
 	var skipped int

sytest-blacklist

@@ -21,4 +21,8 @@ Guest users can accept invites to private rooms over federation
 
 # Tests Synapse specific behavior
 /state returns M_NOT_FOUND for an outlier
-/state_ids returns M_NOT_FOUND for an outlier
+/state_ids returns M_NOT_FOUND for an outlier
+
+# this is a silly restriction as it basically stops servers from communicating, so we relax it
+# see https://github.com/element-hq/synapse/issues/7543
+Server rejects invalid JSON in a version 6 room