diff --git a/bridgev2/bridgeconfig/config.go b/bridgev2/bridgeconfig/config.go
index 13ec738c..01819945 100644
--- a/bridgev2/bridgeconfig/config.go
+++ b/bridgev2/bridgeconfig/config.go
@@ -77,6 +77,7 @@ type BridgeConfig struct {
 	DeduplicateMatrixMessages bool             `yaml:"deduplicate_matrix_messages"`
 	CrossRoomReplies          bool             `yaml:"cross_room_replies"`
 	OutgoingMessageReID       bool             `yaml:"outgoing_message_re_id"`
+	RevertFailedStateChanges  bool             `yaml:"revert_failed_state_changes"`
 	CleanupOnLogout           CleanupOnLogouts `yaml:"cleanup_on_logout"`
 	Relay                     RelayConfig      `yaml:"relay"`
 	Permissions               PermissionConfig `yaml:"permissions"`
diff --git a/bridgev2/bridgeconfig/upgrade.go b/bridgev2/bridgeconfig/upgrade.go
index 6533338f..be8a8f96 100644
--- a/bridgev2/bridgeconfig/upgrade.go
+++ b/bridgev2/bridgeconfig/upgrade.go
@@ -40,6 +40,7 @@ func doUpgrade(helper up.Helper) {
 	helper.Copy(up.Bool, "bridge", "mute_only_on_create")
 	helper.Copy(up.Bool, "bridge", "deduplicate_matrix_messages")
 	helper.Copy(up.Bool, "bridge", "cross_room_replies")
+	helper.Copy(up.Bool, "bridge", "revert_failed_state_changes")
 	helper.Copy(up.Bool, "bridge", "cleanup_on_logout", "enabled")
 	helper.Copy(up.Str, "bridge", "cleanup_on_logout", "manual", "private")
 	helper.Copy(up.Str, "bridge", "cleanup_on_logout", "manual", "relayed")
diff --git a/bridgev2/errors.go b/bridgev2/errors.go
index 76668a99..a06f30ed 100644
--- a/bridgev2/errors.go
+++ b/bridgev2/errors.go
@@ -54,6 +54,7 @@ var (
 	ErrReactionsNotSupported           error = WrapErrorInStatus(errors.New("this bridge does not support reactions")).WithIsCertain(true).WithErrorAsMessage().WithErrorReason(event.MessageStatusUnsupported)
 	ErrPollsNotSupported               error = WrapErrorInStatus(errors.New("this bridge does not support polls")).WithIsCertain(true).WithErrorAsMessage().WithErrorReason(event.MessageStatusUnsupported)
 	ErrRoomMetadataNotSupported        error = WrapErrorInStatus(errors.New("this bridge does not support changing room metadata")).WithIsCertain(true).WithErrorAsMessage().WithSendNotice(false).WithErrorReason(event.MessageStatusUnsupported)
+	ErrRoomMetadataNotAllowed          error = WrapErrorInStatus(errors.New("changes are not allowed here")).WithIsCertain(true).WithErrorAsMessage().WithSendNotice(false).WithErrorReason(event.MessageStatusUnsupported)
 	ErrRedactionsNotSupported          error = WrapErrorInStatus(errors.New("this bridge does not support deleting messages")).WithIsCertain(true).WithErrorAsMessage().WithErrorReason(event.MessageStatusUnsupported)
 	ErrUnexpectedParsedContentType     error = WrapErrorInStatus(errors.New("unexpected parsed content type")).WithErrorAsMessage().WithIsCertain(true).WithSendNotice(true)
 	ErrInvalidStateKey                 error = WrapErrorInStatus(errors.New("room metadata state key is unset or non-empty")).WithErrorAsMessage().WithIsCertain(true).WithSendNotice(false)
diff --git a/bridgev2/matrix/connector.go b/bridgev2/matrix/connector.go
index 64b5d6c7..edd98045 100644
--- a/bridgev2/matrix/connector.go
+++ b/bridgev2/matrix/connector.go
@@ -361,6 +361,7 @@ func (br *Connector) ensureConnection(ctx context.Context) {
 			*br.AS.SpecVersions = *versions
 			br.Capabilities.AutoJoinInvites = br.SpecVersions.Supports(mautrix.BeeperFeatureAutojoinInvites)
 			br.Capabilities.BatchSending = br.SpecVersions.Supports(mautrix.BeeperFeatureBatchSending)
+			br.Capabilities.ArbitraryMemberChange = br.SpecVersions.Supports(mautrix.BeeperFeatureArbitraryMemberChange)
 			break
 		}
 	}
diff --git a/bridgev2/matrix/intent.go b/bridgev2/matrix/intent.go
index ab59a582..27892fb6 100644
--- a/bridgev2/matrix/intent.go
+++ b/bridgev2/matrix/intent.go
@@ -90,8 +90,8 @@ func (as *ASIntent) SendMessage(ctx context.Context, roomID id.RoomID, eventType
 }
 
 func (as *ASIntent) fillMemberEvent(ctx context.Context, roomID id.RoomID, userID id.UserID, content *event.Content) {
-	targetContent := content.Parsed.(*event.MemberEventContent)
-	if targetContent.Displayname != "" || targetContent.AvatarURL != "" {
+	targetContent, ok := content.Parsed.(*event.MemberEventContent)
+	if !ok || targetContent.Displayname != "" || targetContent.AvatarURL != "" {
 		return
 	}
 	memberContent, err := as.Matrix.StateStore.TryGetMember(ctx, roomID, userID)
diff --git a/bridgev2/matrix/mxmain/example-config.yaml b/bridgev2/matrix/mxmain/example-config.yaml
index d8634028..aeb5b7db 100644
--- a/bridgev2/matrix/mxmain/example-config.yaml
+++ b/bridgev2/matrix/mxmain/example-config.yaml
@@ -47,6 +47,8 @@ bridge:
     # Should cross-room reply metadata be bridged?
     # Most Matrix clients don't support this and servers may reject such messages too.
     cross_room_replies: false
+    # If a state event fails to bridge, should the bridge revert any state changes made by that event?
+    revert_failed_state_changes: false
 
     # What should be done to portal rooms when a user logs out or is logged out?
     # Permitted values:
diff --git a/bridgev2/matrixinterface.go b/bridgev2/matrixinterface.go
index 6fa5360c..e8489dc1 100644
--- a/bridgev2/matrixinterface.go
+++ b/bridgev2/matrixinterface.go
@@ -23,8 +23,9 @@ import (
 )
 
 type MatrixCapabilities struct {
-	AutoJoinInvites bool
-	BatchSending    bool
+	AutoJoinInvites       bool
+	BatchSending          bool
+	ArbitraryMemberChange bool
 }
 
 type MatrixConnector interface {
diff --git a/bridgev2/portal.go b/bridgev2/portal.go
index 4943ab00..67199ada 100644
--- a/bridgev2/portal.go
+++ b/bridgev2/portal.go
@@ -520,6 +520,9 @@ func (portal *Portal) handleSingleEvent(ctx context.Context, rawEvt any, doneCal
 				portal.sendSuccessStatus(ctx, evt.evt, 0, "")
 			}
 		}
+		if res.Error != nil && evt.evt.StateKey != nil {
+			portal.revertRoomMeta(ctx, evt.evt)
+		}
 	case *portalRemoteEvent:
 		res = portal.handleRemoteEvent(ctx, evt.source, evt.evtType, evt.evt)
 	case *portalCreateEvent:
@@ -1562,9 +1565,13 @@ func handleMatrixRoomMeta[APIType any, ContentType any](
 	if evt.StateKey == nil || *evt.StateKey != "" {
 		return EventHandlingResultFailed.WithMSSError(ErrInvalidStateKey)
 	}
+	//caps := sender.Client.GetCapabilities(ctx, portal)
+	//if stateCap, ok := caps.State[evt.Type.Type]; !ok || stateCap.Level <= event.CapLevelUnsupported {
+	//	return EventHandlingResultIgnored.WithMSSError(fmt.Errorf("%s %w", evt.Type.Type, ErrRoomMetadataNotAllowed))
+	//}
 	api, ok := sender.Client.(APIType)
 	if !ok {
-		return EventHandlingResultIgnored.WithMSSError(ErrRoomMetadataNotSupported)
+		return EventHandlingResultIgnored.WithMSSError(fmt.Errorf("%w of type %s", ErrRoomMetadataNotSupported, evt.Type))
 	}
 	log := zerolog.Ctx(ctx)
 	content, ok := evt.Content.Parsed.(ContentType)
@@ -1598,7 +1605,6 @@ func handleMatrixRoomMeta[APIType any, ContentType any](
 			return EventHandlingResultIgnored
 		}
 		if !sender.Client.GetCapabilities(ctx, portal).DisappearingTimer.Supports(typedContent) {
-			portal.sendRoomMeta(ctx, nil, time.Now(), event.StateBeeperDisappearingTimer, "", portal.Disappear.ToEventContent(), false)
 			return EventHandlingResultFailed.WithMSSError(ErrDisappearingTimerUnsupported)
 		}
 	}
@@ -1621,9 +1627,6 @@ func handleMatrixRoomMeta[APIType any, ContentType any](
 	})
 	if err != nil {
 		log.Err(err).Msg("Failed to handle Matrix room metadata")
-		if evt.Type == event.StateBeeperDisappearingTimer {
-			portal.sendRoomMeta(ctx, nil, time.Now(), event.StateBeeperDisappearingTimer, "", portal.Disappear.ToEventContent(), false)
-		}
 		return EventHandlingResultFailed.WithMSSError(err)
 	}
 	if changed {
@@ -3891,7 +3894,7 @@ func (portal *Portal) updateName(
 	}
 	portal.Name = name
 	portal.NameSet = portal.sendRoomMeta(
-		ctx, sender, ts, event.StateRoomName, "", &event.RoomNameEventContent{Name: name}, excludeFromTimeline,
+		ctx, sender, ts, event.StateRoomName, "", &event.RoomNameEventContent{Name: name}, excludeFromTimeline, nil,
 	)
 	return true
 }
@@ -3904,7 +3907,7 @@ func (portal *Portal) updateTopic(
 	}
 	portal.Topic = topic
 	portal.TopicSet = portal.sendRoomMeta(
-		ctx, sender, ts, event.StateTopic, "", &event.TopicEventContent{Topic: topic}, excludeFromTimeline,
+		ctx, sender, ts, event.StateTopic, "", &event.TopicEventContent{Topic: topic}, excludeFromTimeline, nil,
 	)
 	return true
 }
@@ -3935,7 +3938,7 @@ func (portal *Portal) updateAvatar(
 		portal.AvatarHash = newHash
 	}
 	portal.AvatarSet = portal.sendRoomMeta(
-		ctx, sender, ts, event.StateRoomAvatar, "", &event.RoomAvatarEventContent{URL: portal.AvatarMXC}, excludeFromTimeline,
+		ctx, sender, ts, event.StateRoomAvatar, "", &event.RoomAvatarEventContent{URL: portal.AvatarMXC}, excludeFromTimeline, nil,
 	)
 	return true
 }
@@ -4003,8 +4006,8 @@ func (portal *Portal) UpdateBridgeInfo(ctx context.Context) {
 		return
 	}
 	stateKey, bridgeInfo := portal.getBridgeInfo()
-	portal.sendRoomMeta(ctx, nil, time.Now(), event.StateBridge, stateKey, &bridgeInfo, false)
-	portal.sendRoomMeta(ctx, nil, time.Now(), event.StateHalfShotBridge, stateKey, &bridgeInfo, false)
+	portal.sendRoomMeta(ctx, nil, time.Now(), event.StateBridge, stateKey, &bridgeInfo, false, nil)
+	portal.sendRoomMeta(ctx, nil, time.Now(), event.StateHalfShotBridge, stateKey, &bridgeInfo, false, nil)
 }
 
 func (portal *Portal) UpdateCapabilities(ctx context.Context, source *UserLogin, implicit bool) bool {
@@ -4026,7 +4029,7 @@ func (portal *Portal) UpdateCapabilities(ctx context.Context, source *UserLogin,
 		Str("old_id", portal.CapState.ID).
 		Str("new_id", capID).
 		Msg("Sending new room capability event")
-	success := portal.sendRoomMeta(ctx, nil, time.Now(), event.StateBeeperRoomFeatures, portal.getBridgeInfoStateKey(), caps, false)
+	success := portal.sendRoomMeta(ctx, nil, time.Now(), event.StateBeeperRoomFeatures, portal.getBridgeInfoStateKey(), caps, false, nil)
 	if !success {
 		return false
 	}
@@ -4037,7 +4040,7 @@ func (portal *Portal) UpdateCapabilities(ctx context.Context, source *UserLogin,
 	}
 	if caps.DisappearingTimer != nil && !portal.CapState.Flags.Has(database.CapStateFlagDisappearingTimerSet) {
 		zerolog.Ctx(ctx).Debug().Msg("Disappearing timer capability was added, sending disappearing timer state event")
-		success = portal.sendRoomMeta(ctx, nil, time.Now(), event.StateBeeperDisappearingTimer, "", portal.Disappear.ToEventContent(), true)
+		success = portal.sendRoomMeta(ctx, nil, time.Now(), event.StateBeeperDisappearingTimer, "", portal.Disappear.ToEventContent(), true, nil)
 		if !success {
 			return false
 		}
@@ -4076,11 +4079,14 @@ func (portal *Portal) sendRoomMeta(
 	stateKey string,
 	content any,
 	excludeFromTimeline bool,
+	extra map[string]any,
 ) bool {
 	if portal.MXID == "" {
 		return false
 	}
-	extra := make(map[string]any)
+	if extra == nil {
+		extra = make(map[string]any)
+	}
 	if excludeFromTimeline {
 		extra["com.beeper.exclude_from_timeline"] = true
 	}
@@ -4106,6 +4112,46 @@ func (portal *Portal) sendRoomMeta(
 	return true
 }
 
+func (portal *Portal) revertRoomMeta(ctx context.Context, evt *event.Event) {
+	if !portal.Bridge.Config.RevertFailedStateChanges {
+		return
+	}
+	if evt.GetStateKey() != "" && evt.Type != event.StateMember {
+		return
+	}
+	switch evt.Type {
+	case event.StateRoomName:
+		portal.sendRoomMeta(ctx, nil, time.Time{}, event.StateRoomName, "", &event.RoomNameEventContent{Name: portal.Name}, true, nil)
+	case event.StateRoomAvatar:
+		portal.sendRoomMeta(ctx, nil, time.Time{}, event.StateRoomAvatar, "", &event.RoomAvatarEventContent{URL: portal.AvatarMXC}, true, nil)
+	case event.StateTopic:
+		portal.sendRoomMeta(ctx, nil, time.Time{}, event.StateTopic, "", &event.TopicEventContent{Topic: portal.Topic}, true, nil)
+	case event.StateBeeperDisappearingTimer:
+		portal.sendRoomMeta(ctx, nil, time.Time{}, event.StateBeeperDisappearingTimer, "", portal.Disappear.ToEventContent(), true, nil)
+	case event.StateMember:
+		var prevContent *event.MemberEventContent
+		var extra map[string]any
+		if evt.Unsigned.PrevContent != nil {
+			_ = evt.Unsigned.PrevContent.ParseRaw(evt.Type)
+			prevContent = evt.Unsigned.PrevContent.AsMember()
+			newContent := evt.Content.AsMember()
+			if prevContent.Membership == newContent.Membership {
+				return
+			}
+			extra = evt.Unsigned.PrevContent.Raw
+		} else {
+			prevContent = &event.MemberEventContent{Membership: event.MembershipLeave}
+		}
+		if portal.Bridge.Matrix.GetCapabilities().ArbitraryMemberChange {
+			if extra == nil {
+				extra = make(map[string]any)
+			}
+			extra["com.beeper.member_rollback"] = true
+			portal.sendRoomMeta(ctx, nil, time.Time{}, event.StateMember, evt.GetStateKey(), prevContent, true, extra)
+		}
+	}
+}
+
 func (portal *Portal) getInitialMemberList(ctx context.Context, members *ChatMemberList, source *UserLogin, pl *event.PowerLevelsEventContent) (invite, functional []id.UserID, err error) {
 	if members == nil {
 		invite = []id.UserID{source.UserMXID}
@@ -4490,6 +4536,7 @@ func (portal *Portal) UpdateDisappearingSetting(
 		"",
 		setting.ToEventContent(),
 		opts.ExcludeFromTimeline,
+		nil,
 	)
 
 	if !opts.SendNotice {
@@ -4618,7 +4665,7 @@ func (portal *Portal) UpdateInfo(ctx context.Context, info *ChatInfo, source *Us
 	}
 	if info.JoinRule != nil {
 		// TODO change detection instead of spamming this every time?
-		portal.sendRoomMeta(ctx, sender, ts, event.StateJoinRules, "", info.JoinRule, info.ExcludeChangesFromTimeline)
+		portal.sendRoomMeta(ctx, sender, ts, event.StateJoinRules, "", info.JoinRule, info.ExcludeChangesFromTimeline, nil)
 	}
 	if info.Type != nil && portal.RoomType != *info.Type {
 		if portal.MXID != "" && (*info.Type == database.RoomTypeSpace || portal.RoomType == database.RoomTypeSpace) {
diff --git a/bridgev2/portalinternal.go b/bridgev2/portalinternal.go
index d9373eb6..749ee389 100644
--- a/bridgev2/portalinternal.go
+++ b/bridgev2/portalinternal.go
@@ -289,8 +289,12 @@ func (portal *PortalInternals) SendStateWithIntentOrBot(ctx context.Context, sen
 	return (*Portal)(portal).sendStateWithIntentOrBot(ctx, sender, eventType, stateKey, content, ts)
 }
 
-func (portal *PortalInternals) SendRoomMeta(ctx context.Context, sender MatrixAPI, ts time.Time, eventType event.Type, stateKey string, content any, excludeFromTimeline bool) bool {
-	return (*Portal)(portal).sendRoomMeta(ctx, sender, ts, eventType, stateKey, content, excludeFromTimeline)
+func (portal *PortalInternals) SendRoomMeta(ctx context.Context, sender MatrixAPI, ts time.Time, eventType event.Type, stateKey string, content any, excludeFromTimeline bool, extra map[string]any) bool {
+	return (*Portal)(portal).sendRoomMeta(ctx, sender, ts, eventType, stateKey, content, excludeFromTimeline, extra)
+}
+
+func (portal *PortalInternals) RevertRoomMeta(ctx context.Context, evt *event.Event) {
+	(*Portal)(portal).revertRoomMeta(ctx, evt)
 }
 
 func (portal *PortalInternals) GetInitialMemberList(ctx context.Context, members *ChatMemberList, source *UserLogin, pl *event.PowerLevelsEventContent) (invite, functional []id.UserID, err error) {
diff --git a/versions.go b/versions.go
index 0392532e..8c1c49aa 100644
--- a/versions.go
+++ b/versions.go
@@ -70,13 +70,14 @@ var (
 	FeatureUnstableProfileFields  = UnstableFeature{UnstableFlag: "uk.tcpip.msc4133"}
 	FeatureArbitraryProfileFields = UnstableFeature{UnstableFlag: "uk.tcpip.msc4133.stable", SpecVersion: SpecV116}
 
-	BeeperFeatureHungry               = UnstableFeature{UnstableFlag: "com.beeper.hungry"}
-	BeeperFeatureBatchSending         = UnstableFeature{UnstableFlag: "com.beeper.batch_sending"}
-	BeeperFeatureRoomYeeting          = UnstableFeature{UnstableFlag: "com.beeper.room_yeeting"}
-	BeeperFeatureAutojoinInvites      = UnstableFeature{UnstableFlag: "com.beeper.room_create_autojoin_invites"}
-	BeeperFeatureArbitraryProfileMeta = UnstableFeature{UnstableFlag: "com.beeper.arbitrary_profile_meta"}
-	BeeperFeatureAccountDataMute      = UnstableFeature{UnstableFlag: "com.beeper.account_data_mute"}
-	BeeperFeatureInboxState           = UnstableFeature{UnstableFlag: "com.beeper.inbox_state"}
+	BeeperFeatureHungry                = UnstableFeature{UnstableFlag: "com.beeper.hungry"}
+	BeeperFeatureBatchSending          = UnstableFeature{UnstableFlag: "com.beeper.batch_sending"}
+	BeeperFeatureRoomYeeting           = UnstableFeature{UnstableFlag: "com.beeper.room_yeeting"}
+	BeeperFeatureAutojoinInvites       = UnstableFeature{UnstableFlag: "com.beeper.room_create_autojoin_invites"}
+	BeeperFeatureArbitraryProfileMeta  = UnstableFeature{UnstableFlag: "com.beeper.arbitrary_profile_meta"}
+	BeeperFeatureAccountDataMute       = UnstableFeature{UnstableFlag: "com.beeper.account_data_mute"}
+	BeeperFeatureInboxState            = UnstableFeature{UnstableFlag: "com.beeper.inbox_state"}
+	BeeperFeatureArbitraryMemberChange = UnstableFeature{UnstableFlag: "com.beeper.arbitrary_member_change"}
 )
 
 func (versions *RespVersions) Supports(feature UnstableFeature) bool {